1
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Avadanei M, Brunchi CE. Wheat gliadin/xanthan gum intermolecular complexes: Interaction mechanism and structural characterization. Food Chem 2024; 460:140619. [PMID: 39067426 DOI: 10.1016/j.foodchem.2024.140619] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/15/2024] [Revised: 07/10/2024] [Accepted: 07/22/2024] [Indexed: 07/30/2024]
Abstract
In this study, the interactions between wheat gliadin (GL) and xanthan gum (XG) were investigated to design new systems with potential applications as a gluten-free substitute product. Combining spectral with morphological and molecular docking methods allowed the establishment of the complexation mechanism between globular hydrophobic GL and the hydrophilic XG with an extended and partially disordered backbone. GL maintains intact its hydrophobic core even at high GL/XG ratios and organizes into small aggregate-type assemblies. The stable and uniform complexes have a low GL content, based on intermolecular hydrogen bonds and hydrophobic interactions. The GL/XG combining ratio influences the size, structure and interaction mechanism of the microparticles. The preferred sites of interaction and the binding affinities were determined by molecular docking on GL libraries and XG models. This research may provide significant knowledge for the development of low-GL wheat food products using a dietary fiber polysaccharide as a functional compound.
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Affiliation(s)
- Mihaela Avadanei
- "Petru Poni" Institute of Macromolecular Chemistry, 41A, Grigore Ghica Voda Alley, 700487, Iasi, Romania
| | - Cristina-Eliza Brunchi
- "Petru Poni" Institute of Macromolecular Chemistry, 41A, Grigore Ghica Voda Alley, 700487, Iasi, Romania.
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2
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Zhang X, Ni N, Fei Z, Li X, Yang W, Siqin Q, Wang Z, Zhang Z. Effect of L-cysteine on the physicochemical properties of heat-induced sheep plasma protein gels. Food Chem 2024; 444:138508. [PMID: 38340502 DOI: 10.1016/j.foodchem.2024.138508] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/06/2023] [Revised: 01/02/2024] [Accepted: 01/17/2024] [Indexed: 02/12/2024]
Abstract
The effects of different l-Cysteine additions (0-2 %) on the gel properties, microstructure and physicochemical stability of sheep plasma protein gels were studied. The introduction of l-Cys significantly improved the water retention capacity and whiteness of the plasma protein gel (p < 0.05). The addition of 0.2 %-0.4 % l-Cys increased gel strength, but l-Cys had no significant effect on gel elasticity (p < 0.05). Scanning electron microscopy confirmed that the addition of l-Cys also promoted the formation of a porous three-dimensional network structure in the gel. Raman spectroscopy and SDS-PAGE revealed that the addition of l-Cys generally reduced α-helix structures in protein gels and promoted the formation of β-folds. Addition of 0.2 % l-Cys treatment leading to the greatest increase in disulfide bonds, and its surface hydrophobicity and endogenous fluorescence intensity were the largest. At this time, the comprehensive performance of sheep plasma protein gel is the best performance.
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Affiliation(s)
- Xudong Zhang
- School of Life Sciences and Food, Inner Mongolia Minzu University, Tongliao 028000, China; Institute of Agro-products Processing Science and Technology, Chinese Academy of Agricultural Sciences/Key Laboratory of Agro-products Processing, Ministry of Agriculture, Beijing 100193, China
| | - Na Ni
- School of Life Sciences and Food, Inner Mongolia Minzu University, Tongliao 028000, China.
| | - Zixuan Fei
- School of Life Sciences and Food, Inner Mongolia Minzu University, Tongliao 028000, China
| | - Xiaoxue Li
- School of Life Sciences and Food, Inner Mongolia Minzu University, Tongliao 028000, China
| | - Wanpeng Yang
- School of Life Sciences and Food, Inner Mongolia Minzu University, Tongliao 028000, China
| | - Qimuge Siqin
- School of Life Sciences and Food, Inner Mongolia Minzu University, Tongliao 028000, China
| | - Zhenyu Wang
- Institute of Agro-products Processing Science and Technology, Chinese Academy of Agricultural Sciences/Key Laboratory of Agro-products Processing, Ministry of Agriculture, Beijing 100193, China
| | - Zhiyong Zhang
- Tongliao Academy of Agricultural Sciences, Tongliao, Inner Mongolia 028015, China
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3
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Ma J, Pan D, Dong Y, Diao J, Chen H. The Effectiveness of Clove Extract on Oxidization-Induced Changes of Structure and Gelation in Porcine Myofibrillar Protein. Foods 2022; 11:foods11131970. [PMID: 35804785 PMCID: PMC9265466 DOI: 10.3390/foods11131970] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/01/2022] [Revised: 06/27/2022] [Accepted: 06/30/2022] [Indexed: 02/06/2023] Open
Abstract
This study aimed to investigate the structural characteristics and gelation behavior of myofibrillar proteins (MPs) with or without clove extract (CE) at different oxidation times (0, 1, 3, and 5 h). Circular dichroism spectra and Fourier transform infrared spectra showed that samples with CE addition had significantly higher α-helix content after oxidation than those without CE addition. However, prolonged oxidation (5 h) would make the effect of CE addition less pronounced. Similarly, the ultraviolet-visible (UV) spectra analysis revealed that CE controlled the oxidative stretching of the protein tertiary structure and reduced the exposure of aromatic amino acids. In addition, the particle size and turbidity values of the CE group significantly decreased after oxidation compared to the non-CE group. CE increased the gel strength by 10.05% after 5 h of oxidation, which could be observed by scanning electron microscopy (SEM) as a more homogeneous, dense, less porous, network-like gel structure. Therefore, these results showed that oxidation induced significant changes in the structure and gel properties of MPs, but the addition of CE effectively inhibited these destructive changes.
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Affiliation(s)
- Jinming Ma
- College of Food Science, Heilongjiang Bayi Agricultural University, Daqing 163319, China; (J.M.); (D.P.)
| | - Deyin Pan
- College of Food Science, Heilongjiang Bayi Agricultural University, Daqing 163319, China; (J.M.); (D.P.)
| | - Ying Dong
- Huangpu Customs Technology Center, Dongguan 523000, China;
| | - Jingjing Diao
- National Coarse Cereals Engineering Research Center, Heilongjiang Bayi Agricultural University, Daqing 163319, China;
| | - Hongsheng Chen
- College of Food Science, Heilongjiang Bayi Agricultural University, Daqing 163319, China; (J.M.); (D.P.)
- China-Canada Cooperation Agri-Food Research Center of Heilongjiang Province, Daqing 163319, China
- Correspondence:
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4
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Wang R, Ma Y, Zhang L, Zhang Z, Chi Y, Chi Y. Changes in egg yolk gelation behaviour and mechanisms during freezing. Lebensm Wiss Technol 2021. [DOI: 10.1016/j.lwt.2021.112223] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/20/2022]
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5
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Zhang M, Li F, Diao X, Kong B, Xia X. Moisture migration, microstructure damage and protein structure changes in porcine longissimus muscle as influenced by multiple freeze-thaw cycles. Meat Sci 2017; 133:10-18. [DOI: 10.1016/j.meatsci.2017.05.019] [Citation(s) in RCA: 164] [Impact Index Per Article: 23.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/24/2017] [Revised: 05/19/2017] [Accepted: 05/25/2017] [Indexed: 11/29/2022]
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6
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Effect of low frequency ultrasonication on biochemical and structural properties of chicken actomyosin. Food Chem 2016; 205:43-51. [DOI: 10.1016/j.foodchem.2016.03.003] [Citation(s) in RCA: 35] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/25/2015] [Revised: 02/11/2016] [Accepted: 03/01/2016] [Indexed: 11/20/2022]
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7
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Yan W, Xu B, Jia F, Dai R, Li X. The Effect of High-Pressure Carbon Dioxide on the Skeletal Muscle Myoglobin. FOOD BIOPROCESS TECH 2016. [DOI: 10.1007/s11947-016-1747-5] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
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8
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Karunathilaka SR, Farris S, Mossoba MM, Moore JC, Yakes BJ. Characterising variances of milk powder and instrumentation for the development of a non-targeted, Raman spectroscopy and chemometrics detection method for the evaluation of authenticity. Food Addit Contam Part A Chem Anal Control Expo Risk Assess 2016; 33:921-32. [PMID: 27167451 PMCID: PMC4918629 DOI: 10.1080/19440049.2016.1188437] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/24/2016] [Accepted: 04/29/2016] [Indexed: 01/20/2023]
Abstract
There is a need to develop rapid tools to screen milk products for economically motivated adulteration. An understanding of the physiochemical variability within skim milk powder (SMP) and non-fat dry milk (NFDM) is the key to establishing the natural differences of these commodities prior to the development of non-targeted detection methods. This study explored the sources of variance in 71 commercial SMP and NFDM samples using Raman spectroscopy and principal component analysis (PCA) and characterised the largest number of commercial milk powders acquired from a broad number of international manufacturers. Spectral pre-processing using a gap-segment derivative transformation (gap size = 5, segment width = 9, fourth derivative) in combination with sample normalisation was necessary to reduce the fluorescence background of the milk powder samples. PC scores plots revealed no clear trends for various parameters, including day of analysis, powder type, supplier and processing temperatures, while the largest variance was due to irreproducibility in sample positioning. Significant chemical sources of variances were explained by using the spectral features in the PC loadings plots where four samples from the same manufacturer were determined to likely contain an additional component or lactose anomers, and one additional sample was identified as an outlier and likely containing an adulterant or differing quality components. The variance study discussed herein with this large, diverse set of milk powders holds promise for future use as a non-targeted screening method that could be applied to commercial milk powders.
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Affiliation(s)
- Sanjeewa R. Karunathilaka
- US Food and Drug Administration (USFDA), Center for Food Safety and Applied Nutrition, Office of Regulatory Science, College Park, MD, USA
| | - Samantha Farris
- US Food and Drug Administration (USFDA), Center for Food Safety and Applied Nutrition, Office of Regulatory Science, College Park, MD, USA
| | - Magdi M. Mossoba
- US Food and Drug Administration (USFDA), Center for Food Safety and Applied Nutrition, Office of Regulatory Science, College Park, MD, USA
| | | | - Betsy Jean Yakes
- US Food and Drug Administration (USFDA), Center for Food Safety and Applied Nutrition, Office of Regulatory Science, College Park, MD, USA
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9
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Zhdanova NG, Shirshin EA, Maksimov EG, Panchishin IM, Saletsky AM, Fadeev VV. Tyrosine fluorescence probing of the surfactant-induced conformational changes of albumin. Photochem Photobiol Sci 2015; 14:897-908. [DOI: 10.1039/c4pp00432a] [Citation(s) in RCA: 39] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/06/2023]
Abstract
Tyrosine fluorescence in native proteins is known to be effectively quenched, whereas its emission increases upon proteins’ unfolding.
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Affiliation(s)
- Nadezda G. Zhdanova
- Department of Physics
- M.V. Lomonosov Moscow State University
- Moscow 119991
- Russia
| | - Evgeny A. Shirshin
- Department of Physics
- M.V. Lomonosov Moscow State University
- Moscow 119991
- Russia
| | - Eugene G. Maksimov
- Department of Biology
- M.V. Lomonosov Moscow State University
- Moscow 119991
- Russia
| | - Ivan M. Panchishin
- Department of Physics
- M.V. Lomonosov Moscow State University
- Moscow 119991
- Russia
| | | | - Victor V. Fadeev
- Department of Physics
- M.V. Lomonosov Moscow State University
- Moscow 119991
- Russia
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10
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Phase separation behavior and structural analysis of ovalbumin–gum arabic complex coacervation. Food Hydrocoll 2015. [DOI: 10.1016/j.foodhyd.2014.02.009] [Citation(s) in RCA: 48] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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11
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Orel M, Padrós E, Manyosa J. Structural features of the C-terminus from the human neurokinin-1 receptor. FEBS J 2012; 279:2357-67. [DOI: 10.1111/j.1742-4658.2012.08614.x] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/26/2023]
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12
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Merlino A, Russo Krauss I, Rossi B, Vergara A, De Vendittis A, Marco S, De Vendittis E, Sica F. Identification of an active dimeric intermediate populated during the unfolding process of the cambialistic superoxide dismutase from Streptococcus mutans. Biochimie 2012; 94:768-75. [DOI: 10.1016/j.biochi.2011.11.008] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/11/2011] [Accepted: 11/18/2011] [Indexed: 10/15/2022]
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13
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Risso VA, Primo ME, Brunet JE, Sotomayor CP, Ermácora MR. Optical studies of single-tryptophan B. licheniformis beta-lactamase variants. Biophys Chem 2010; 151:111-8. [PMID: 20561743 DOI: 10.1016/j.bpc.2010.05.013] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/16/2010] [Revised: 05/27/2010] [Accepted: 05/27/2010] [Indexed: 11/30/2022]
Abstract
beta-lactamases (penicillinases) are important complicating factors in bacterial infections and excellent theoretical and experimental models in protein structure, dynamics and evolution. Bacillus licheniformis exo-small penicillinase (ESP) is a Class A beta-lactamase with three tryptophan residues, one located in each of the two protein domains and one located in the interface between domains. To determine the tryptophan contribution to the ESP UV-absorption, circular dichroism, and steady-state and time-resolved fluorescence, four Trp-->Phe mutants were prepared and characterized. The residue substitutions had little impact on the native conformation. UV-absorption and CD features were identified and ascribed to specific aromatic residues. Time-resolved fluorescence showed that most of the fluorescence decay of ESP tryptophans is due to a discrete exponential component with a lifetime of 5-6ns. Fluorescence polarization measurements indicated that fluorescence of Trp 210 is nearly independent of the fluorescence of Trp 229 and Trp 251, whereas a substantial energy homotransfer between the latter pair takes place. The spectroscopic information was rationalized on the basis of structural considerations and should help in the interpretation and monitoring of the changes at the sub domain level during the conformational transitions and fluctuations of ESP and other Class A beta-lactamases.
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Affiliation(s)
- Valeria A Risso
- Departamento de Ciencia y Tecnología, Universidad Nacional de Quilmes, Buenos Aires, Argentina
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14
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A spectroscopic investigation into the interaction between bile salts and insulin in alkaline aqueous solution. J Colloid Interface Sci 2009; 337:322-31. [DOI: 10.1016/j.jcis.2009.05.056] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/06/2009] [Revised: 05/13/2009] [Accepted: 05/22/2009] [Indexed: 11/22/2022]
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15
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Jiang J, Chen J, Xiong YL. Structural and emulsifying properties of soy protein isolate subjected to acid and alkaline pH-shifting processes. JOURNAL OF AGRICULTURAL AND FOOD CHEMISTRY 2009; 57:7576-83. [PMID: 19601630 DOI: 10.1021/jf901585n] [Citation(s) in RCA: 320] [Impact Index Per Article: 21.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/13/2023]
Abstract
Structural unfolding of soy protein isolate (SPI) as induced by holding (0, 0.5, 1, 2, and 4 h) in acidic (pH 1.5-3.5) and alkaline (pH 10.0-12.0) pH solutions, followed by refolding (1 h) at pH 7.0, was analyzed. Changes in emulsifying properties of treated SPI were then examined. The pH-shifting treatments resulted in a substantial increase in protein surface hydrophobicity, intrinsic tryptophan fluorescence intensity, and disulfide-mediated aggregation, along with the exposure of tyrosine. After the pH-shifting processes, soy protein adopted a molten globule-like conformation that largely maintained the original secondary structure and overall compactness but lost some tertiary structure. These structural modifications, consequently, led to markedly improved emulsifying activity of SPI as well as the emulsion stability.
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Affiliation(s)
- Jiang Jiang
- State Key Laboratory of Food Science and Technology and School of Food Science and Technology, Jiangnan University, Jiangsu, China
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16
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KALIMAN PERLA, ERMÁCORA MARIOR, NOWICKI CRISTINA, WOLFENSTEIN-TODEL CARLOTA, SANTOMÉ JOSÉA. Chemical modification of human growth hormone with N-acetylimidazole. ACTA ACUST UNITED AC 2009. [DOI: 10.1111/j.1399-3011.1991.tb01407.x] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
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17
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The effect of pulsed electric fields on the inactivation and structure of lysozyme. Food Chem 2008; 110:334-43. [DOI: 10.1016/j.foodchem.2008.02.008] [Citation(s) in RCA: 64] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/20/2007] [Revised: 12/27/2007] [Accepted: 02/04/2008] [Indexed: 11/22/2022]
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18
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Thermal stability of CopA, a polytopic membrane protein from the hyperthermophile Archaeoglobus fulgidus. Arch Biochem Biophys 2008; 471:198-206. [DOI: 10.1016/j.abb.2007.12.013] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/24/2007] [Revised: 12/19/2007] [Accepted: 12/20/2007] [Indexed: 11/21/2022]
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19
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Kornblatt JA, Barretto TA, Chigogidze K, Chirwa B. Canine Plasminogen: Spectral Responses to Changes in 6-Aminohexanoate and Temperature. ANALYTICAL CHEMISTRY INSIGHTS 2007. [DOI: 10.4137/117739010700200009] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
Abstract
We studied the near UV absorption spectrum of canine plasminogen. There are 19 tryptophans, 19 phenylalanines and 34 tyrosines in the protein. 4th derivative spectra optimized for either tryptophan or tyrosine give a measure of the polarity of the environments of these two aromatic amino acids. Plasminogen at temperatures between 0°C and 37°C exists as a mixture of four conformations: closed-relaxed, open-relaxed, closed-compact, and open-compact. The closed to open transition is driven by addition of ligand to a site on the protein. The relaxed to compact transition is driven by increasing temperature from 0°C to above 15-20°C. When the conformation of plasminogen is mainly closed-relaxed, the 4th derivative spectra suggest that the average tryptophan environment is similar to a solution of 20% methanol at the same temperature. Under the same conditions, 4th derivative spectra suggest that the average tyrosine environment is similar to water. These apparent polarities change as the plasminogen is forced to assume the other conformations. We try to rationalize the information based on the known portions of the plasminogen structure.
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Affiliation(s)
- Jack A. Kornblatt
- Enzyme Research Group, Department of Biology, Concordia University, Montreal, Qc., Canada H4B 1R6
| | - Tanya A. Barretto
- Enzyme Research Group, Department of Biology, Concordia University, Montreal, Qc., Canada H4B 1R6
| | - Ketevan Chigogidze
- Enzyme Research Group, Department of Biology, Concordia University, Montreal, Qc., Canada H4B 1R6
| | - Bahati Chirwa
- Enzyme Research Group, Department of Biology, Concordia University, Montreal, Qc., Canada H4B 1R6
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20
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Nikolovski Z, Buzón V, Ribó M, Moussaoui M, Vilanova M, Cuchillo CM, Cladera J, Nogués MV. Thermal unfolding of eosinophil cationic protein/ribonuclease 3: a nonreversible process. Protein Sci 2006; 15:2816-27. [PMID: 17088327 PMCID: PMC2242447 DOI: 10.1110/ps.062196406] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/23/2022]
Abstract
Eosinophil cationic protein (ECP)/ribonuclease 3 is a member of the RNase A superfamily involved in inflammatory processes mediated by eosinophils. ECP is bactericidal, helminthotoxic, and cytotoxic to tracheal epithelium cells and to several mammalian cell lines although its RNase activity is low. We studied the thermal stability of ECP by fourth-derivative UV absorbance spectra, circular dichroism, differential scanning calorimetry, and Fourier transform infrared spectroscopy. The T (1/2) values obtained with the different techniques were in very good agreement (T (1/2) approximately 72 degrees C), and the stability was maintained in the pH range between 5 and 7. The ECP calorimetric melting curve showed, in addition to the main transition, a pretransitional conformational change with a T (1/2) of 44 degrees C. Both calorimetric transitions disappeared after successive re-heatings, and the ratio DeltaH versus DeltaH (vH) of 2.2 indicated a significant deviation from the two-state model. It was observed that the thermal unfolding was irreversible. The unfolding process gives rise to changes in the environment of aromatic amino acids that are partially maintained in the refolded protein with the loss of secondary structure and the formation of oligomers. From the thermodynamic analysis of ECP variants, the contribution of specific amino acids, such as Trp10 and the region 115-122, to thermal stability was also determined. The high thermal stability of ECP may contribute to its resistance to degradation when the protein is secreted to the extracellular medium during the immune response.
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Affiliation(s)
- Zoran Nikolovski
- Unitat de Bioquímica, Facultat de Ciències, Universitat Autònoma de Barcelona, 08193 Bellaterra, Spain
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21
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Lucas LH, Ersoy BA, Kueltzo LA, Joshi SB, Brandau DT, Thyagarajapuram N, Peek LJ, Middaugh CR. Probing protein structure and dynamics by second-derivative ultraviolet absorption analysis of cation-{pi} interactions. Protein Sci 2006; 15:2228-43. [PMID: 16963649 PMCID: PMC2242397 DOI: 10.1110/ps.062133706] [Citation(s) in RCA: 42] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/24/2022]
Abstract
We describe an alternate approach for studying protein structure using the detection of ultraviolet (UV) absorbance peak shifts of aromatic amino acid side chains induced by the presence of salts. The method is based on the hypothesis that salt cations (Li+, Na+, and Cs+) of varying sizes can differentially diffuse through protein matrices and interact with benzyl, phenyl, and indole groups through cation-pi interactions. We have investigated the potential of this method to probe protein dynamics by measuring high resolution second-derivative UV spectra as a function of salt concentration for eight proteins of varying physical and chemical properties and the N-acetylated C-ethyl esterified amino acids to represent totally exposed side chains. We show that small shifts in the wavelength maxima for Phe, Tyr, and Trp in the presence of high salt concentrations can be reliably measured and that the magnitude and direction of the peak shifts are influenced by several factors, including protein size, charge, and the local environment and solvent accessibility of the aromatic groups. Evaluating the empirical UV spectral data in light of known protein structural information shows that probing cation-pi interactions in proteins reveals unique information about the influence of structure on aromatic side chain spectroscopic behavior.
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Affiliation(s)
- Laura H Lucas
- Department of Pharmaceutical Chemistry, University of Kansas, Lawrence, Kansas 66047, USA
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22
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del Valle LJ, Escribano C, Pérez JJ, Garriga P. Calcium-induced decrease of the thermal stability and chaperone activity of alpha-crystallin. BIOCHIMICA ET BIOPHYSICA ACTA 2002; 1601:100-9. [PMID: 12429508 DOI: 10.1016/s1570-9639(02)00429-6] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
Alpha-crystallin, one of the major proteins in the vertebrate eye lens, acts as a molecular chaperone, like the small heat-shock proteins, by protecting other proteins from denaturing under stress or high temperature conditions. alpha-Crystallin aggregation is involved in lens opacification, and high [Ca(2+)] has been associated with cataract formation, suggesting a role for this cation in the pathological process. We have investigated the effect of Ca(2+) on the thermal stability of alpha-crystallin by UV and Fourier-transform infrared (FTIR) spectroscopies. In both cases, a Ca(2+)-induced decrease in the midpoint of the thermal transition is detected. The presence of high [Ca(2+)] results also in a marked decrease of its chaperone activity in an insulin-aggregation assay. Furthermore, high Ca(2+) concentration decreases Cys reactivity towards a sulfhydryl reagent. The results obtained from the spectroscopic analysis, and confirmed by circular dichroism (CD) measurements, indicate that Ca(2+) decreases both secondary and tertiary-quaternary structure stability of alpha-crystallin. This process is accompanied by partial unfolding of the protein and a clear decrease in its chaperone activity. It is concluded that Ca(2+) alters the structural stability of alpha-crystallin, resulting in impaired chaperone function and a lower protective ability towards other lens proteins. Thus, alpha-crystallin aggregation facilitated by Ca(2+) would play a role in the progressive loss of transparency of the eye lens in the cataractogenic process.
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Affiliation(s)
- Luis J del Valle
- Departament d'Enginyeria Química, Universitat Politècnica de Catalunya, Colom 1, 08222 Terrassa, Catalonia, Spain
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23
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Clérico EM, Ermácora MR. Tryptophan mutants of intestinal fatty acid-binding protein: ultraviolet absorption and circular dichroism studies. Arch Biochem Biophys 2001; 395:215-24. [PMID: 11697859 DOI: 10.1006/abbi.2001.2554] [Citation(s) in RCA: 18] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
An UV absorption and CD study of intestinal fatty acid-binding protein is presented. Since there are only two Trp residues in the molecule, two single-Trp mutants were prepared to deconvolute their signals. The individual contribution of the eight Phe and four Tyr residues was not established; however, Phe global contribution is relatively free of interferences from the other chromophores and was observed directly. CD spectra showed that Phe vibronic structure was unusually sharp and seems to monitor very specific details in the three-dimensional structure. The global signal from Tyr was assigned only approximately due to band broadening and overlapping. At the upper end of the CD spectrum, strong positive (1)L(b) Trp transitions from Trp 82 and strong negative (1)L(b) Trp transitions from Trp 6 were observed. (1)L(a) transitions were overall weak, positive for Trp 82 and negative for Trp 6, nearly cancelling each other out in the final spectrum. The above assignment is of practical and fundamental interest to monitor folding, binding, and molecular dynamics down to microdomain resolution. The assignment of Trp bands allowed comparison with previous data from CRABP1, another member of the IFABP family with 28% identical residues. It was found that structural homology extends beyond sequence and tertiary fold to include optical properties of equivalent Trp residues in the structure.
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Affiliation(s)
- E M Clérico
- Departamento de Ciencia y Tecnología, Universidad Nacional de Quilmes, Roque Sáenz Peña 180, 1876 Bernal, Argentina
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24
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Ceolín M, Colombo US, Frate MC, Clérico E, Antón E, Ermácora MR. Head-to-tail and side-by-side oligomerization of human carbonic anhydrase II: a small angle X-ray scattering study. Int J Biol Macromol 2001; 28:143-50. [PMID: 11164231 DOI: 10.1016/s0141-8130(00)00155-0] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
Abstract
Solvent-induced directional aggregation of human carbonic anhydrase II (hCA) was studied by small angle X-ray scattering and fluorescence and fourth-derivative ultraviolet absorption spectroscopy. We propose that hCA at 5 mg ml(-1) in pure water forms head-to-tail oligomers built up, on average, by four to five monomers. At higher protein concentrations, the oligomers associate pair-wise and side-by-side. Spectroscopic evidence suggests that the subunits forming the aggregates are tightly folded, but with a structure that differs, at least locally, from the native state. A more complex aggregation pattern was observed under solvent conditions that favor the removal of zinc from the enzyme-active site, conditions under which the subunits are significantly less compact than in water. hCA may provide a useful model to investigate the effects of additives and genetic manipulation on protein aggregation.
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Affiliation(s)
- M Ceolín
- Departamento de Física, Facultad de Ciencias Exactas, Universidad Nacional de La Plata, C.C.67, 1900, La Plata, Argentina.
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25
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Di Pietro SM, Santomé JA. Isolation, characterization and binding properties of two rat liver fatty acid-binding protein isoforms. BIOCHIMICA ET BIOPHYSICA ACTA 2000; 1478:186-200. [PMID: 10825530 DOI: 10.1016/s0167-4838(00)00042-x] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
Abstract
Mammalian liver has only one fatty acid-binding protein (L-FABP) while the liver of non-mammalian vertebrates expresses a liver basic FABP (Lb-FABP) in addition to other members of the FABP family. We explore the possibility that L-FABP isoforms accomplish, in the liver of mammals, the metabolic functions corresponding to the different FABPs present in the liver of non-mammalian vertebrates. We have isolated isoforms I and II which have a different residue 105, Asn in the former and Asp in the latter. We made a conformational comparison of the apo-isoforms by intrinsic fluorescence emission and fourth-derivative spectroscopy, native-state proteolysis and unfolding curves. Ligand affinity was studied by measuring cis-parinaric acid displacement by different ligands. They have differences in their molecular conformation, including the environment of the binding site. Isoform II has probably a more open conformation than isoform I, thus allowing the binding of a greater variety of ligands. The affinity of isoform II for lysophospholipids, prostaglandins, retinoids, bilirubin and bile salts is greater than that of isoform I. These characteristics of rat L-FABP isoforms I and II suggest that they may accomplish different functions as happens with those of the different FABP types in non-mammalian species.
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Affiliation(s)
- S M Di Pietro
- Instituto de Química y Fisicoquímica Biológicas, Facultad de Farmacia y Bioquímica, Universidad de Buenos Aires, Junín 956, 1113, Buenos Aires, Argentina.
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26
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Clérico EM, Peisajovich SG, Ceolín M, Ghiringhelli PD, Ermácora MR. Engineering a compact non-native state of intestinal fatty acid-binding protein. BIOCHIMICA ET BIOPHYSICA ACTA 2000; 1476:203-18. [PMID: 10669786 DOI: 10.1016/s0167-4838(99)00247-2] [Citation(s) in RCA: 19] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
The last three C-terminal residues (129-131) of intestinal fatty acid-binding protein (IFABP) participate in four main-chain hydrogen bonds and two electrostatic interactions to sequentially distant backbone and side-chain atoms. To assess if these interactions are involved in the final adjustment of the tertiary structure during folding, we engineered an IFABP variant truncated at residue 128. An additional mutation, Trp-6-->Phe, was introduced to simplify the conformational analysis by optical methods. Although the changes were limited to a small region of the protein surface, they resulted in an IFABP with altered secondary and tertiary structure. Truncated IFABP retains some cooperativity, is monomeric, highly compact, and has the molecular dimensions and shape of the native protein. Our results indicated that residues 129-131 are part of a crucial conformational determinant in which several long-range interactions, essential for the acquisition of the native state, are established. This work suggests that carefully controlled truncation can populate equilibrium non-native states under physiological conditions. These non-native states hold a great promise as experimental models for protein folding.
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Affiliation(s)
- E M Clérico
- Departamento de Ciencia y Tecnología, Universidad Nacional de Quilmes, Argentina, Roque Sáenz Peña 180, (1876), Bernal, Argentina
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27
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Arighi CN, Rossi JP, Delfino JM. Temperature-induced conformational transition of intestinal fatty acid binding protein enhancing ligand binding: a functional, spectroscopic, and molecular modeling study. Biochemistry 1998; 37:16802-14. [PMID: 9843451 DOI: 10.1021/bi981827x] [Citation(s) in RCA: 24] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Intestinal fatty acid binding protein (IFABP) undergoes a reversible thermal transition between 35 and 50 degreesC, as revealed by circular dichroism spectroscopy in the near-UV region. For the apoprotein, the molar ellipticity measured at 254 nm (possibly implicating the environment around F17 and/or F55) decreases significantly in this temperature range, while in the holoprotein (bound to oleic acid), this phenomenon is not observed. Concomitantly, an increase in the activity of binding to [14C]oleic acid occurs. Nevertheless, other spectroscopic evidence indicates that the beta-barrel structure, the major motif of this protein, is highly stable up to 70 degreesC. No changes associated with conformation were detected for both structures by fourth-derivative analysis of the UV absorption spectra, circular dichroism in the far-UV region, and intrinsic fluorescence measurements. Further structural information arises from experiments in which binding to the anionic fluorescent probes 1-anilinonaphthalene-8-sulfonic acid (ANS) and its dimer bisANS was examined. The fluorescence intensity of bound ANS diminishes monotonically, whereas that of bisANS increases slightly in the temperature range of 35-50 degreesC. Given the different size of these probes, model building suggests that ANS would be able to sense regions located deeply inside the cavity, while bisANS could also reach the vicinity of the small helical domain of this protein. In light of these results, we believe that this subtle conformational transition of IFABP, which positively influences the binding activity, would involve fluctuations at the peripheral "entry portal" region for the ligand. This interpretation is compatible with the discrete disorder observed in this place in apo-IFABP, as evidenced by NMR spectroscopy [Hodsdon, M. E., and Cistola, D. P. (1997) Biochemistry 36, 1450-1460].
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Affiliation(s)
- C N Arighi
- Department of Biological Chemistry, Institute of Biochemistry and Biophysics (IQUIFIB), University of Buenos Aires, Argentina
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28
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Mora-García S, Rodríguez-Suárez R, Wolosiuk RA. Role of electrostatic interactions on the affinity of thioredoxin for target proteins. Recognition of chloroplast fructose-1, 6-bisphosphatase by mutant Escherichia coli thioredoxins. J Biol Chem 1998; 273:16273-80. [PMID: 9632687 DOI: 10.1074/jbc.273.26.16273] [Citation(s) in RCA: 47] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Chloroplast thioredoxin-f functions efficiently in the light-dependent activation of chloroplast fructose-1, 6-bisphosphatase by reducing a specific disulfide bond located at the negatively charged domain of the enzyme. Around the nucleophile cysteine of the active site (-W-C-G-P-C-), chloroplast thioredoxin-f shows lower density of negative charges than the inefficient modulator Escherichia coli thioredoxin. To examine the contribution of long range electrostatic interactions to the thiol/disulfide exchange between protein-disulfide oxidoreductases and target proteins, we constructed three variants of E. coli thioredoxin in which an acidic (Glu-30) and a neutral residue (Leu-94) were replaced by lysines. After purification to homogeneity, the reduction of the unique disulfide bond by NADPH via NADP-thioredoxin reductase proceeded at similar rates for all variants. However, the conversion of cysteine residues back to cystine depended on the target protein. Insulin and difluoresceinthiocarbamyl-insulin oxidized the sulfhydryl groups of E30K and E30K/L94K mutants more effectively than those of wild type and L94K counterparts. Moreover, the affinity of E30K, L94K, and E30K/L94K E. coli thioredoxin for chloroplast fructose-1,6-bisphosphatase (A0.5 = 9, 7, and 3 microM, respectively) increased with the number of positive charges, and was higher than wild type thioredoxin (A0.5 = 33 microM), though still lower than that of thioredoxin-f (A0.5 = 0.9 microM). We also demonstrated that shielding of electrostatic interactions with high salt concentrations not only brings the A0.5 for all bacterial variants to a limiting value of approximately 9 microM but also increases the A0.5 of chloroplast thioredoxin-f. While negatively charged chloroplast fructose-1,6-bisphosphatase (pI = 4.9) readily interacted with mutant thioredoxins, the reduction rate of rapeseed napin (pI = 11.2) diminished with the number of novel lysine residues. These findings suggest that the electrostatic interactions between thioredoxin and (some of) its target proteins controls the formation of the binary noncovalent complex needed for the subsequent thiol/disulfide exchange.
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Affiliation(s)
- S Mora-García
- Instituto de Investigaciones Bioquímicas, Fundación Campomar, Facultad de Ciencias Exactas y Naturales-Universidad de Buenos Aires, Argentina
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29
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Study of ionization of tyrosine residues in proteins by second-derivative UV spectroscopy. Russ Chem Bull 1997. [DOI: 10.1007/bf02495938] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
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30
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Cymes GD, Wolfenstein-Todel C. Identification of a tyrosine residue in ovine placental lactogen as essential for its binding to receptors. BIOCHIMICA ET BIOPHYSICA ACTA 1996; 1294:31-6. [PMID: 8639711 DOI: 10.1016/0167-4838(95)00260-x] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/01/2023]
Abstract
Nitration of ovine placental lactogen (oPL) with a 10-fold molar excess of tetranitromethane over protein content resulted in the modification of 0.8 tyrosine residue. No conformational changes were observed by either fourth-derivative spectral analysis or circular dichroism. Nitration significantly decreased the binding capacity of the hormone to lactogenic and somatogenic rat liver receptors. This binding capacity was not restored by reduction of the nitro groups, thus indicating that the decrease was not due to the difference in pK between tyrosine and nitrotyrosine. The nitrotyrosine-containing peptide was isolated from a tryptic digest by HPLC and its modification extent was of 67%, which is consistent with the decrease in binding capacities (65% and 70%). Its amino acid sequence was determined and the modified tyrosine residue was identified as Tyr-46. These results provide the first evidence of the involvement of a tyrosine residue in the binding of oPL to both lactogenic and somatogenic receptors. This tyrosine appears to be a shared binding epitope between oPL and the prolactins.
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Affiliation(s)
- G D Cymes
- Instituto de Química y Fisicoquímica Biólogicas, Buenos Aires, Argentina
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31
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Mora-García S, Ballícora MA, Wolosiuk RA. Chloroplast fructose-1,6-bisphosphatase: modification of non-covalent interactions promote the activation by chimeric Escherichia coli thioredoxins. FEBS Lett 1996; 380:123-6. [PMID: 8603719 DOI: 10.1016/0014-5793(96)00022-1] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/31/2023]
Abstract
Although all thioredoxins contain a highly conserved amino acid sequence responsible for thiol/disulfide exchanges, only chloroplast thioredoxin-f is effective in the reductive stimulation of chloroplast fructose-1,6-bisphosphatase. We set out to determine whether Escherichia coli thioredoxin becomes functional when selected modulators alter the conformation of the target enzyme. Wild type and chimeric Escherichia coli thioredoxins match the chloroplast counterpart when the activation of chloroplast fructose 1,6-biphosphatase is performed in the presence of fructose 1,6-bisphosphate, Ca2+, and either trichloroacetate or 2-propanol. These modulators of enzyme activity do change the conformation of chloroplast fructose-1,6-bisphosphatase whereas bacterial thioredoxins remain unaltered. Given that fructose 1,6-bisphosphate, Ca2+, and non-physiological perturbants modify non-covalent interactions of the protein but do not participate in redox reactions, these results strongly suggest that the conformation of the target enzyme regulates the rate of thiol/disulfide exchanges catalyzed by protein disulfide oxidoreductases.
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Affiliation(s)
- S Mora-García
- Instituto de Investigaciones Bioquímicas (Fundación Campomar, I.I.B.-F.C.E.N.-U.B.A., IIBBA-CONICET), Buenos Aires, Argentina
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32
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Daniel Lacorazza H, Otero de Bengtsson MS, Biscoglio de Jiménez Bonino MJ. Key histidine residues in the nicotinic acetylcholine receptor. Neurochem Int 1996; 28:77-87. [PMID: 8746767 DOI: 10.1016/0197-0186(95)00055-d] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/01/2023]
Abstract
Reactivity of histidine residues of the Discopyge tschudii nicotinic acetylcholine receptor was studied by reaction with DEP and the influence of their modification on functional properties of the receptor was evaluated. Determination of two kinetically distinguishable classes was achieved. The fast-reacting class is composed of 7 histidine residues with an apparent velocity constant k1 = 0.0248 +/- 0.0031 min-1. The second includes--at least--21 histidine residues with a velocity constant k2 = 0.0016 +/- 0.0009 min-1. The circular dichroism spectra of the native receptor and the most DEP-derivative indicate no significant modifications in the alpha-helix content, and fourth derivative spectroscopy analyses show that the environment around the aromatic amino acids remains unchanged. DEP treatment of the receptor results in a time- and reagent concentration-dependent loss of its alpha-bungarotoxin binding ability; these results agree with those obtained with the membrane-bound receptor. The decrease in the neurotoxin binding capacity was correlated with the DEP-reaction extent of the slow groups. Incorporation of 1.93 +/- 0.23 mol of DEP accounted for the maximal binding capacity drop, thus indicating the involvement of two histidine residues per alpha-bungarotoxin binding site. Neither amino groups nor tyrosine residues were modified during the reaction with DEP, indicating that the derivatization of histidine residues is responsible for the observed effect. Faster-reacting residues appear to be involved in agonist-induced ion flux through the nAChR channel. These results strongly support the connection between histidine residues and the receptor functional activity and lead us to infer that the changes observed in alpha-bungarotoxin binding and ionic channel capacity are the consequence of independent events induced by reaction with DEP.
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Affiliation(s)
- H Daniel Lacorazza
- Instituto de Química y Fisicoquímica Biológicas, (UBA-CONICET), Buenos Aires, Argentina
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33
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Ballicora MA, Wolosiuk RA. Enhancement of the reductive activation of chloroplast fructose-1,6-bisphosphatase by modulators and protein perturbants. EUROPEAN JOURNAL OF BIOCHEMISTRY 1994; 222:467-74. [PMID: 8020485 DOI: 10.1111/j.1432-1033.1994.tb18887.x] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/28/2023]
Abstract
To characterize the mechanism of chloroplast fructose-1,6-bisphosphatase activation, we have examined kinetic and structural changes elicited by protein perturbants and reductants. At variance with its well-known capacity for enzyme inactivation, 150 mM sodium trichloroacetate yielded an activatable chloroplast fructose-1,6-bisphosphatase in the presence of 1.0 mM fructose 1,6-bisphosphate and 0.1 mM Ca2+. Other sugar bisphosphates did not replace fructose 1,6-bisphosphate whereas Mg2+ and Mn2+ were functional in place of Ca2+. Variations of the emission fluorescence of intrinsic fluorophores and a noncovalently bound extrinsic probe [2-(p-toluidinyl)naphthalene-6-sulfonate] indicated the presence of conformations different from the native form. A similar conclusion was drawn from the analysis of absorption spectra by means of fourth-derivative spectrophotometry. The effect of these conformational changes on the reductive process was studied by subsequently incubating the enzyme with dithiothreitol. The reaction of chloroplast fructose-1,6-bisphosphatase with dithiothreitol was accelerated 13-fold by the chaotropic anion: second-order rate constants were 48.1 M-1.min-1 and 3.7 M-1.min-1 in the presence and in the absence of trichloroacetate, respectively. Thus, the enhancement of the reductive activation by compounds devoid of redox activity illustrated that the modification of intramolecular noncovalent interactions of chloroplast fructose-1,6-bisphosphatase plays an essential role in the conversion of enzyme disulfide bonds to sulfhydryl groups. In consequence, a conformational change would operate concertedly with the reduction of disulfide bridges in the light-dependent activation mediated by the ferredoxin-thioredoxin system.
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Affiliation(s)
- M A Ballicora
- Instituto de Investigaciones Bioquímicas Fundación Campomar, IIBBA-CONICET, FCEN-UBA, Buenos Aires, Argentina
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34
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Cymes GD, Iglesias MM, Wolfenstein-Todel C. Chemical modification of ovine prolactin with N-acetylimidazole. INTERNATIONAL JOURNAL OF PEPTIDE AND PROTEIN RESEARCH 1993; 42:33-8. [PMID: 8370641 DOI: 10.1111/j.1399-3011.1993.tb00346.x] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/30/2023]
Abstract
Reaction of ovine prolactin (oPRL) with a 150-fold molar excess of N-acetylimidazole over protein content resulted in the modification of 2.5 tyrosine residues and 1.2 lysine residues. Acetylation greatly decreased the in vitro binding capacity to lactogenic sites. This binding capacity was partially restored by ammonium bicarbonate treatment, which removes O-acetyl groups from tyrosine residues but not N-acetyl groups from lysine residues. The modification extent of the tyrosine residues was determined. The results suggest that acetylation of tyrosine 44 or of tyrosine 96 is likely to be responsible for the decrease in binding activity of acetylated oPRL, and that one of these residues may play a role in the interaction of oPRL with lactogenic receptors.
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Affiliation(s)
- G D Cymes
- Instituto de Química y Fisicoquímica Biológicas (UBA-CONICET), Faculty of Pharmacy and Biochemistry, Buenos Aires, Argentina
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35
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Sousa MC, Ferrero-Garcia MA, Parodi AJ. Recognition of the oligosaccharide and protein moieties of glycoproteins by the UDP-Glc:glycoprotein glucosyltransferase. Biochemistry 1992; 31:97-105. [PMID: 1531024 DOI: 10.1021/bi00116a015] [Citation(s) in RCA: 248] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
Abstract
It was found, in cell-free assays, that the Man8GlcNAc2 and Man7GlcNAc2 isomers having the mannose unit to which the glucose is added were glucosylated by the rat liver glucosyltransferase at 50 and 15%, respectively, of the rate of Man9GlcNAc2 glucosylation. This indicates that processing by endoplasmic reticulum mannosidases decreases the extent of glycoprotein glucosylation. All five different glycoproteins tested (bovine and porcine thyroglobulins, phytohemagglutinin, soybean agglutinin, and bovine pancreas ribonuclease B) were found to be poorly glucosylated or not glucosylated unless they were subjected to treatments that modified their native conformations. The effect of denaturation was not to expose the oligosaccharides but to make protein determinants, required for enzymatic activity, accessible to the glucosyltransferase because (a) cleavage of denatured glycoproteins by unspecific (Pronase) or specific (trypsin) proteases abolished their glucose acceptor capacities almost completely except when the tryptic peptides were held together by disulfide bonds and (b) high mannose oligosaccharides in native glycoproteins, although poorly glucosylated or not glucosylated, were accessible to macromolecular probes as concanavalin A-Sepharose, endo-beta-N-acetylglucosaminidase H, and jack bean alpha-mannosidase. In addition, denatured, endo-beta-N-acetylglucosaminidase H deglycosylated glycoproteins were found to be potent inhibitors of the glucosylation of denatured glycoproteins. It is suggested that in vivo only unfolded, partially folded, and malfolded glycoproteins are glucosylated and that glucosylation stops upon adoption of the correct conformation, a process that hides the protein determinants (possibly hydrophobic amino acids) from the glucosyltransferase.
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Affiliation(s)
- M C Sousa
- Instituto de Investigaciones Bioquimicas, Fundación Campomar, Buenos Aires, Argentina
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36
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Kishigami A, Sekiya N, Yoshihara K, Hara R, Hara T, Tokunaga F. SPECTROSCOPIC STUDIES ON THE STRUCTURES OF RETINOCHROME and METARETINOCHROME. Photochem Photobiol 1991. [DOI: 10.1111/j.1751-1097.1991.tb02121.x] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
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37
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Brewster ME, Hora MS, Simpkins JW, Bodor N. Use of 2-hydroxypropyl-beta-cyclodextrin as a solubilizing and stabilizing excipient for protein drugs. Pharm Res 1991; 8:792-5. [PMID: 2062811 DOI: 10.1023/a:1015870521744] [Citation(s) in RCA: 128] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
Abstract
A chemically modified, amorphous beta-cyclodextrin, namely, 2-hydroxypropyl-beta-cyclodextrin (HPCD), was examined as a solubilizing and stabilizing agent for protein drugs. The aqueous solubility of ovine growth hormone at pH 7.4 was increased through the use of HPCD. This effect was manifested by higher UV transparency at 600 nm. Interleukin-2 (IL-2) is rendered insoluble upon lyophilization in the absence of stabilizers. Use of aqueous HPCD provides a clear solution, as indicated by fluorometric light scattering, and inhibits aggregate formation, as shown by ultracentrifugation and Western blot analyses. In addition, there were no major conformational changes of IL-2 in HPCD formulation as indicated by fourth-derivative ultraviolet spectroscopy. Finally, IL-2 retained 100% of its biopotency when prepared in HPCD solutions. Aggregation of insulin was also suppressed by HPCD. These data, as well as the i.v. safety of HPCD and its well-characterized chemical composition, suggest that this starch derivative may be a potentially useful excipient for protein drugs intended for parenteral use.
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Affiliation(s)
- M E Brewster
- Center for Drug Design and Delivery, University of Florida, Gainesville 32610
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38
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Mozo-Villarías A, Morros A, Andreu JM. Thermal transitions in the structure of tubulin. Environments of aromatic aminoacids. EUROPEAN BIOPHYSICS JOURNAL : EBJ 1991; 19:295-300. [PMID: 1915154 DOI: 10.1007/bf00183318] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
Abstract
The environment of aromatic aminoacids in the thermal transition of brain tubulin has been studied by several spectroscopic techniques (Fourth Derivative, Difference Absorption, Fluorescence and Circular Dichroism), in order to study its denaturation. An irreversible, temperature-induced, structural transition was found at around 48 degrees C. In order to establish the relative degree of hydrophobicity of tubulin aromatic residues, before and after the thermal transition, difference and fourth derivative absorption spectra at different temperatures were compared with spectra of tyrosine and tryptophan model compounds in different media. It was found that at high temperatures, tubulin acquires a partially denatured stable state, with a significant amount of residual structure still preserved. This state is characterized by a general increase of the exposure of tyrosine residues to the medium, while the environment of tryptophans becomes more hydrophobic.
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Affiliation(s)
- A Mozo-Villarías
- Department de Ciencies Mèdiques Bàsiques, Facultat de Medicina, Universitat de Barcelona, Lleida, Spain
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39
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Garriga P, Sági J, Garcia-Quintana D, Sabés M, Manyosa J. Conformational isomerizations of the poly(dA-dT) and poly(amino2dA-dT) duplexes involving the unusual X-DNA double helix: a fourth derivative spectrophotometric study. J Biomol Struct Dyn 1990; 7:1061-71. [PMID: 2360998 DOI: 10.1080/07391102.1990.10508546] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
Fourth derivative spectrophotometry has been applied to monitor conformational isomerizations of polynucleotides for the first time. The transitions studied have been the B-A and A-X isomerizations of poly(dA-dT) and the B-X one of poly(amino2dA-dT). Parameters obtained from the fourth derivative spectra have been used to follow these conformational changes. The A form of poly(dA-dT) has been characterized by a new fourth derivative peak at 293.0 nm which can be associated to interstrand adenine-adenine interactions. Furthermore, some of the fourth derivative peaks in the long wavelength region (270-310 nm) can be related to stacking interactions present in the polynucleotide double helices. The tentative assignment of these peaks, particularly that at 299.0 nm in the derivative spectra of poly(amino2dA-dT), to n----pi electronic transitions is discussed.
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Affiliation(s)
- P Garriga
- Departament de Bioquimica i Biologia Molecular, Facultat de Medicina, Universitat Autònoma de Barcelona, Spain
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40
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Wilson C, Matthews F, Greasham RL, Will M, Copeland RA. Application of fourth derivative absorption spectroscopy to protein quantitation during purification. Anal Biochem 1989; 182:141-5. [PMID: 2513738 DOI: 10.1016/0003-2697(89)90731-8] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
Abstract
A method for protein quantitation in the presence of nonprotein cellular components is described. The method is based on measurement of two tryptophan-specific signals in the fourth derivative of the protein's ultraviolet absorption spectrum, a peak at 283 nm and a trough at 288 nm. The amplitude between these two extremes is shown to vary linearly with protein concentration for bovine serum albumin and the outer membrane vesicles of Neissera meningitidis even when these protein solutions are supplemented with enough nucleic acid to completely obscure the parent absorption spectrum of the protein. The utility of this method as an in-process assay during isolation of a protein is demonstrated by comparing estimates of protein content from fourth derivative spectroscopy with those from the Lowry assay for samples at several steps along the isolation pathway for outer membrane vesicles of N. meningitidis. The advantages and limitations of the present method are discussed.
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Affiliation(s)
- C Wilson
- Merck Sharp and Dohme Research Laboratories, Rahway, New Jersey 07065
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41
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Sabés M, Padrós E. DETECTION OF CHARGE-PERTURBATION OF TRYPTOPHAN RESIDUES BY FOURTH-DERIVATIVE SPECTROPHOTOMETRY. Photochem Photobiol 1987. [DOI: 10.1111/j.1751-1097.1987.tb07394.x] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
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Libertini LJ, Small EW. The intrinsic tyrosine fluorescence of histone H1. Steady state and fluorescence decay studies reveal heterogeneous emission. Biophys J 1985; 47:765-72. [PMID: 4016197 PMCID: PMC1435174 DOI: 10.1016/s0006-3495(85)83979-5] [Citation(s) in RCA: 41] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023] Open
Abstract
In wavelength-resolved steady state spectra we observe three different kinds of emission from histone H1, a class A protein with only a single tyrosine residue. Unfolded H1 emissions that peak at approximately 300 and 340 nm can both be excited maximally at approximately 280 nm. Another, peaking much further to the red at approximately 400 nm, can be excited maximally at approximately 320 nm. The 300-nm fluorescence can be resolved by lifetime measurements into three components with decay times of approximately 1, 2, and 4 ns. On sodium-chloride-induced refolding of H1, simplification of the emission properties occurs. The 340 and 400-nm components disappear while the two shorter lifetime components of the 300-nm band diminish in amplitude and are replaced by the 4-ns decay. We believe that the 340-nm emission is tyrosinate fluorescence resulting from excited-state proton transfer. The origin of the 400-nm emission remains uncertain. We assign the 1 and 2-ns components of the 300-nm emission to two states of tyrosine in denatured H1 and the 4-ns decay to fluorescence of the single tyrosine residue in the globular region of refolded H1. Our results support the contention that salt induced folding of H1 is a cooperative two state process, and permit us to better understand the previously reported increases in fluorescence intensity and anisotropy on salt-induced folding.
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Padrós E, Duñach M, Morros A, Sabés M, Mañosa J. Fourth-derivative spectrophotometry of proteins. Trends Biochem Sci 1984. [DOI: 10.1016/0968-0004(84)90272-x] [Citation(s) in RCA: 25] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
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Padrós E, Duñach M, Sabés M. Induction of the blue form of bacteriorhodopsin by low concentrations of sodium dodecyl sulfate. BIOCHIMICA ET BIOPHYSICA ACTA 1984; 769:1-7. [PMID: 6691969 DOI: 10.1016/0005-2736(84)90002-6] [Citation(s) in RCA: 27] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/21/2023]
Abstract
The effects produced on bacteriorhodopsin by low concentrations of several detergents have been studied by absorption and fourth-derivative spectrophotometry. Sodium dodecyl sulfate induces the appearance of the blue form of bacteriorhodopsin (lambda max = 600 nm) at pH values up to 7.0 in a reversible manner. The apparent pK of the purple-to-blue transition raised with increasing concentration of SDS. Of the other detergents tested, only sodium dodecyl-N-sarcosinate showed a slight red-shift of the absorption band to 580 nm, whereas sodium taurocholate, Triton X-100 and cetyltrimethylammonium bromide did not favour the appearance of the blue form. The effect of SDS was found to be consistent with a localized conformational change that moves away the counter-ion of the protonated Schiff base.
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Duñach M, Sabés M, Padrós E. Fourth-derivative spectrophotometry analysis of tryptophan environment in proteins. Application to melittin, cytochrome c and bacteriorhodopsin. EUROPEAN JOURNAL OF BIOCHEMISTRY 1983; 134:123-8. [PMID: 6305654 DOI: 10.1111/j.1432-1033.1983.tb07540.x] [Citation(s) in RCA: 39] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/19/2023]
Abstract
Fourth-derivative spectrophotometry is applied to the analysis of solvent effects on the spectral transitions of N-acetyl-L-tryptophan amide, as well as of its mixtures with N-acetyl-L-tyrosine ethyl ester. These compounds were analyzed in different media. It was found that the position of the longest-wavelength minimum of the fourth-derivative spectrum is mainly determined by the nature of the Trp environment, with a minor contribution from that of Tyr. A geometrical parameter is also defined, which depends on both Trp and Tyr environments. The simultaneous consideration of both parameters allows an estimation to be made of the Trp environment. The method is applied to the study of conformational changes of three well-characterized proteins: melittin from bee venom, cytochrome c from horse heart and bacteriorhodopsin from Halobacterium halobium. The results obtained are found to be in accordance with the known conformational properties of these proteins. In addition, the fourth-derivative operation completely eliminates the interference from the near-ultraviolet bands of the prosthetic groups.
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