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Gazi I, Reiding KR, Groeneveld A, Bastiaans J, Huppertz T, Heck AJR. LacdiNAc to LacNAc: remodelling of bovine α-lactalbumin N-glycosylation during the transition from colostrum to mature milk. Glycobiology 2024; 34:cwae062. [PMID: 39115362 PMCID: PMC11319639 DOI: 10.1093/glycob/cwae062] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/05/2024] [Revised: 08/05/2024] [Accepted: 08/07/2024] [Indexed: 08/15/2024] Open
Abstract
α -Lactalbumin, an abundant protein present in the milk of most mammals, is associated with biological, nutritional and technological functionality. Its sequence presents N-glycosylation motifs, the occupancy of which is species-specific, ranging from no to full occupancy. Here, we investigated the N-glycosylation of bovine α-lactalbumin in colostrum and milk sampled from four individual cows, each at 9 time points starting from the day of calving up to 28.0 d post-partum. Using a glycopeptide-centric mass spectrometry-based glycoproteomics approach, we identified N-glycosylation at both Asn residues found in the canonical Asn-Xxx-Ser/Thr motif, i.e. Asn45 and Asn74 of the secreted protein. We found similar glycan profiles in all four cows, with partial site occupancies, averaging at 35% and 4% for Asn45 and Asn74, respectively. No substantial changes in occupancy occurred over lactation at either site. Fucosylation, sialylation, primarily with N-acetylneuraminic acid (Neu5Ac), and a high ratio of N,N'-diacetyllactosamine (LacdiNAc)/N-acetyllactosamine (LacNAc) motifs were characteristic features of the identified N-glycans. While no substantial changes occurred in site occupancy at either site during lactation, the glycoproteoform (i.e. glycosylated form of the protein) profile revealed dynamic changes; the maturation of the α-lactalbumin glycoproteoform repertoire from colostrum to mature milk was marked by substantial increases in neutral glycans and the number of LacNAc motifs per glycan, at the expense of LacdiNAc motifs. While the implications of α-lactalbumin N-glycosylation on functionality are still unclear, we speculate that N-glycosylation at Asn74 results in a structurally and functionally different protein, due to competition with the formation of its two intra-molecular disulphide bridges.
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Affiliation(s)
- Inge Gazi
- Biomolecular Mass Spectrometry and Proteomics, Bijvoet Center for Biomolecular Research and Utrecht Institute for Pharmaceutical Sciences, University of Utrecht, Padualaan 8, Utrecht 3584 CH, The Netherlands
- Netherlands Proteomics Center, Padualaan 8, Utrecht 3584 CH, The Netherlands
| | - Karli R Reiding
- Biomolecular Mass Spectrometry and Proteomics, Bijvoet Center for Biomolecular Research and Utrecht Institute for Pharmaceutical Sciences, University of Utrecht, Padualaan 8, Utrecht 3584 CH, The Netherlands
- Netherlands Proteomics Center, Padualaan 8, Utrecht 3584 CH, The Netherlands
| | - André Groeneveld
- Research and Development, FrieslandCampina, Stationsplein 4, Amersfoort 3818 LE, The Netherlands
| | - Jan Bastiaans
- Research and Development, FrieslandCampina, Stationsplein 4, Amersfoort 3818 LE, The Netherlands
| | - Thom Huppertz
- Research and Development, FrieslandCampina, Stationsplein 4, Amersfoort 3818 LE, The Netherlands
- Department of Agrotechnology and Food Sciences, Wageningen University, Bornse Weilanden 9, Wageningen 6708 WG, The Netherlands
| | - Albert J R Heck
- Biomolecular Mass Spectrometry and Proteomics, Bijvoet Center for Biomolecular Research and Utrecht Institute for Pharmaceutical Sciences, University of Utrecht, Padualaan 8, Utrecht 3584 CH, The Netherlands
- Netherlands Proteomics Center, Padualaan 8, Utrecht 3584 CH, The Netherlands
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Claumarchirant L, Sanchez-Siles LM, Matencio E, Alegría A, Lagarda MJ. Evaluation of Sialic Acid in Infant Feeding: Contents and Bioavailability. JOURNAL OF AGRICULTURAL AND FOOD CHEMISTRY 2016; 64:8333-8342. [PMID: 27750424 DOI: 10.1021/acs.jafc.6b03273] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/06/2023]
Abstract
Sialic acid (Sia) contents and bioaccessibility (BA) in human milk (HM) and infant formulas (IFs) were determined, and Sia intakes by infants between 0 and 6 months of age were evaluated. Total Sia contents in HM decreased during lactation from 136.14 to 24.47 mg/100 mL. The total Sia contents in IFs (13.15-25.78 mg/100 mL) were lower than in HM and were not related to the addition of ingredients acting as sources of Sia in their formulation. The Sia intakes derived from IF consumption were lower than in HM, and only one IF reached the intakes provided by HM from the age of 2 months. Despite the lower total Sia content in IFs, the BA of Sia in IFs (88.08-92.96%) was significantly greater than in mature HM (72.51%) and similar to that found in colostrum (96.43%). However, the Sia contents in the available soluble fraction of IFs did not reach those provided by HM.
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Affiliation(s)
- Lorena Claumarchirant
- Nutrition and Food Science Area, Faculty of Pharmacy, University of Valencia , Avenida Vicente Andrés Estellés s/n, 46100 Burjassot (Valencia), Spain
| | - Luis Manuel Sanchez-Siles
- Hero Institute of Infant Nutrition, Hero Group , Avenida Murcia 1, 30820 Alcantarilla (Murcia), Spain
| | - Esther Matencio
- Hero Institute of Infant Nutrition, Hero Group , Avenida Murcia 1, 30820 Alcantarilla (Murcia), Spain
| | - Amparo Alegría
- Nutrition and Food Science Area, Faculty of Pharmacy, University of Valencia , Avenida Vicente Andrés Estellés s/n, 46100 Burjassot (Valencia), Spain
| | - María Jesús Lagarda
- Nutrition and Food Science Area, Faculty of Pharmacy, University of Valencia , Avenida Vicente Andrés Estellés s/n, 46100 Burjassot (Valencia), Spain
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3
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O'Riordan N, Kane M, Joshi L, Hickey RM. Structural and functional characteristics of bovine milk protein glycosylation. Glycobiology 2014; 24:220-36. [PMID: 24398766 DOI: 10.1093/glycob/cwt162] [Citation(s) in RCA: 116] [Impact Index Per Article: 11.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/29/2023] Open
Abstract
Most secreted and cell membrane proteins in mammals are glycosylated. Many of these glycoproteins are also prevalent in milk and play key roles in the biomodulatory properties of milk and ultimately in determining milk's nutritional quality. Although a significant amount of information exists on the types and roles of free oligosaccharides in milk, very little is known about the glycans associated with milk glycoproteins, in particular, the biological properties that are linked to their presence. The main glycoproteins found in bovine milk are lactoferrin, the immunoglobulins, glycomacropeptide, a glycopeptide derived from κ-casein, and the glycoproteins of the milk fat globule membrane. Here, we review the glycoproteins present in bovine milk, the information currently available on their glycosylation and the biological significance of their oligosaccharide chains.
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Affiliation(s)
- Noelle O'Riordan
- Teagasc Food Research Centre, Moorepark, Fermoy, County Cork, Ireland
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4
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Lacomba R, Salcedo J, Alegría A, Barberá R, Hueso P, Matencio E, Lagarda MJ. Sialic acid (N-acetyl and N-glycolylneuraminic acid) and ganglioside in whey protein concentrates and infant formulae. Int Dairy J 2011. [DOI: 10.1016/j.idairyj.2011.05.008] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
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Abstract
During the last decade, marked progress has been made in the study of the fine details of the structures of milk proteins such as caseins, beta-lactoglobulin, alpha-lactalbumin, and lactotransferrin. Many of the functional properties of the individual milk proteins, as well as the milk protein products, may be described at the molecular level. This article is an attempt to thoroughly review the three-dimensional structures of major milk proteins, and to correlate them with the functional aspects of these proteins as food ingredients.
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Affiliation(s)
- D W Wong
- USDA-ARS-WRRC, Albany, California 94710, USA
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8
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Kim HH, Jimenez-Flores R. Comparison of milk proteins using preparative isoelectric focusing followed by polyacrylamide gel electrophoresis. J Dairy Sci 1994; 77:2177-90. [PMID: 7962843 DOI: 10.3168/jds.s0022-0302(94)77160-5] [Citation(s) in RCA: 31] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/28/2023]
Abstract
The major proteins in milks from bovine, caprine, porcine, and murine animals and from humans were compared using a two-dimensional analysis method. In the first dimension, proteins were separated by their isoelectric points using preparative isoelectric focusing in pH gradient of 3 to 10. Twenty fractions from each sample were then analyzed by urea-PAGE and SDS-PAGE. Two-dimensional gels showed characteristic patterns for each milk. Major bovine milk proteins were identified and used as reference for proteins of other mammals. Additionally, some peptides resulting from plasmin hydrolysis were characterized. Caprine milk proteins showed a pattern similar to that of bovine milk except for the absence of alpha s1-caseins. alpha-Lactalbumin of bovine and caprine milks resolved as two bands in an immunoblot using bovine alpha-lactalbumin antibody. Each band corresponded to normal and glycosylated alpha-lactalbumin. Human, porcine, and murine milk proteins were totally different from those of ruminant milks on the two-dimensional gels. Two-dimensional analysis using preparative isoelectric focusing, followed by PAGE, was a useful method to compare major milk proteins in several mammals because of the rapid simultaneous separation into 20 fractions. This fractionation allows additional analytical procedures for more efficient comparison of chemical and physical properties of the proteins.
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Affiliation(s)
- H H Kim
- Department of Food Science, University of Illinois, Urbana 61801
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9
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Abstract
α-Lactalbumin (α-La) is a protein found in the milk of all mammalian species and is involved in lactose biosynthesis in association with galactosyltransferase (Brodbecket al.1967). The primary structure of α-La from several species such as bovine (Brewet al.1970), human (Findlay & Brew, 1972), and goat (McGillivrayet al.1979) has been determined. Hallet al.(1982) have established the nucleotide sequence and the organization of the human α-La gene (Hallet al.1987).
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Affiliation(s)
- F Maynard
- Laboratoire de Recherches de Technologie Laitière, INRA, Rennes, France
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10
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McKenzie HA, White FH. Lysozyme and alpha-lactalbumin: structure, function, and interrelationships. ADVANCES IN PROTEIN CHEMISTRY 1991; 41:173-315. [PMID: 2069076 DOI: 10.1016/s0065-3233(08)60198-9] [Citation(s) in RCA: 177] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
Affiliation(s)
- H A McKenzie
- Department of Chemistry, University College, University of New South Wales, Australian Defence Force Academy, Canberra, ACT, Australia
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11
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Cantisani A, Napolitano L, Giuffrida MG, Conti A. Direct identification and characterization of llama (Lama glama L.) whey proteins by microsequencing after western blotting. JOURNAL OF BIOCHEMICAL AND BIOPHYSICAL METHODS 1990; 21:227-36. [PMID: 2280056 DOI: 10.1016/0165-022x(90)90016-6] [Citation(s) in RCA: 19] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
Amino acid sequence determination is the most reliable and powerful tool to identify a protein or to classify a new one by comparison of its primary structure with already known sequences. A rapid and simple purification procedure is an essential pre-requisite for routine sequence determination. Structural characterization of llama whey proteins was undertaken for evolutionary as well as economic purposes. N-terminal sequence analyses directly on an immobilon polyvinylidene difluoride (PVDF) membrane, following Western blotting of both native and SDS-denatured llama whey proteins after polyacrylamide gel electrophoresis, revealed three different forms of glycosylated alpha-lactalbumin, and a protein with a high degree of homology with a camel whey protein of unknown function. Furthermore, by immunoblotting techniques, the electrophoretic band corresponding to serum albumin was identified.
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Affiliation(s)
- A Cantisani
- Centro Studi Alimentazione Animali, CNR, Torino, Italy
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12
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Thompson MP, Brower DP, Jenness R, Kotts CE. Phylogenetic variations in the calcium-dependent electrophoretic shift of alpha-lactalbumin. J Dairy Sci 1989; 72:3156-65. [PMID: 2628439 DOI: 10.3168/jds.s0022-0302(89)79474-1] [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: 01/01/2023]
Abstract
alpha-Lactalbumin undergoes a calcium-dependent electrophoretic shift at pH 8.3. When Ca2+ is removed by a chelator, the mobility of the protein increases, reflecting the exposure of negative electrical charges. The shift, however, is not observed by electrophoresis in the presence of SDS, which demonstrates that alpha-lactalbumin does not undergo a measurable conformational change upon debinding of Ca2+. Relative electrophoretic mobilities vary from 1.0 (no shift) to 1.4 among alpha-lactalbumins of different orders of mammals. The differences suggest a variable number of gram atoms of Ca2+ bound to alpha-lactalbumin or substitution of amino acid Ca2+ ligands in the calcium-binding loop.
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Affiliation(s)
- M P Thompson
- US Department of Agriculture, Eastern Regional Research Center, Philadelphia, PA 19118
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13
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van den Berg G, Smolders C. Concentration polarization phenomena during dead-end ultrafiltration of protein mixtures. The influence of solute-solute interactions. J Memb Sci 1989. [DOI: 10.1016/s0376-7388(00)80857-1] [Citation(s) in RCA: 27] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
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14
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Thompson MP, Brower DP. The Method of Aschaffenburg and Drewry for the Crystallization of β-Lactoglobulin and α-Lactalbumin. 1. Electrophoresis of Fractions and the Calcium2+/Ethylenebis (Oxyethylenenitrilo) Tetraacetic Acid Shift of α-Lactalbumin. J Dairy Sci 1988. [DOI: 10.3168/jds.s0022-0302(88)79667-8] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
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15
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Eigel W, Butler J, Ernstrom C, Farrell H, Harwalkar V, Jenness R, Whitney RM. Nomenclature of Proteins of Cow's Milk: Fifth Revision. J Dairy Sci 1984. [DOI: 10.3168/jds.s0022-0302(84)81485-x] [Citation(s) in RCA: 635] [Impact Index Per Article: 15.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
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16
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Abstract
We surveyed published reports on about 50 glycoproteins whose amino acid sequence, glycosylation sites, and type of glycosylation at a particular site have been established. We note that high-mannose substances were rarely found at the N-terminal side of a previously glycosylated complex site. There was a very definite distribution of complex sites about the N-terminal region. Furthermore, secreted glycoproteins usually contained only complex oligosaccharides whereas membrane proteins contained both types. We suggest that the position of the glycosylation site with respect to the N-terminus affects the extent of oligosaccharide processing and subsequent presentation of complex or high-mannose structures in the mature glycoprotein. This review relates glycosylation type to its position in the known sequence of given proteins and discusses these observations in light of known glycosylation processing reactions.
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17
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Abstract
The occurrence of the 'whey' protein, alpha-lactalbumin, in pig (Sus scrofus) milk samples from 904 sows is examined. A semi-discontinuous buffer system has been developed to detect the existence of genetic polymorphism. There are two homozygous variants, designated A and B. Both variants are isolated and it is shown by peptide and sequencing studies that the A variant differs from the B variant by having an Arg residue substituted for the Lys residue at the N-terminus of the molecule. The sequence of the first thirty residues is determined and compared with those of related alpha-lactalbumins.
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18
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Sienkiewicz T. Nomenklatur und einige Eigenschaften der Molkenproteine. 2. Mitt. α-Lactalbumin, Immunoglobuline, Proteose-Peptone, Minorproteine und Enzyme. ACTA ACUST UNITED AC 1981. [DOI: 10.1002/food.19810250405] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
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19
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Abstract
alpha-Lactalbumin has been purified from mouse milk by the use of ammonium sulfate precipitation, Bio-Gel P-100 chromatography and DEAE-cellulose chromatography. Mouse alpha-lactalbumin exists as two major charge forms with the same molecular weight. Both charge forms have been used in the development of a radioimmunoassay to mouse alpha-lactalbumin. The assay is specific for mouse alpha-lactalbumin, reacting identically with both forms, and sensitive with a minimal detectable concentration of 0.35 ng. alpha-Lactalbumin induced in mouse mammary gland explants has been measured with the use of the radioimmunoassay and is detectable in both the explants and media of the cultures.
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20
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Nagamatsu Y, Oka T. Purification and characterization of mouse alpha-lactalbumin and preparation of its antibody. Biochem J 1980; 185:227-37. [PMID: 6769429 PMCID: PMC1161289 DOI: 10.1042/bj1850227] [Citation(s) in RCA: 29] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/21/2023]
Abstract
alpha-Lactalbumin was purified to apparent homogeneity from mouse milk by combined use of gel filtration, chromatography on DEAE-cellulose and hydroxyapatite, and concanavalin A-Sepharose affinity chromatography. Mouse alpha-lactalbumin exists in several species with different charges and in two molecular-size forms. The smaller form, which constituted over 90% of total alpha-lactalbumin, included two major and two minor species, each of which showed different electrophoretic mobility on polyacrylamide-gel electrophoresis, but gave the same single band on sodium dodecyl sulphate/polyacrylamide-gel electrophoresis in two different buffer systems and over the range 10-15% acrylamide concentrations. The molecular weight was estimated as 14 100. The two major species of the smaller form had the same amino acid composition and contained no significant amount of carbohydrate. The larger form of alpha-lactalbumin, consisting of two species with different charges, was present in a small amount (less than 10%) in the milk and was isolated by its ability to interact with concanavalin A-Sepharose. Each of the two species also gave the same single band of apparent mol.w.t 18 500 on sodium dodecyl sulphate/polyacrylamide-gel electrophoresis. However, this value may be anomalous, since this larger form appears to be glycosylated, and glycoproteins can behave anomalously on sodium dodecyl sulphate/polyacrylamide gels by binding less sodium dodecyl sulphate. All species of mouse alpha-lactalbumin from milk were active in the lactose synthase reaction and showed identical immunological properties, as determined by the mono-specific antibody prepared against the small major species. The presence of both the larger and the smaller forms, each in a percentage concentration similar to that found in milk, was also demonstrated in alpha-lactalbumin induced by hormones in organ cultureof pregnant-mouse mammary gland.
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21
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Resolution of the charge forms and amino acid sequence and location of a tryptic glycopeptide in rat alpha-lactalbumin. J Biol Chem 1979. [DOI: 10.1016/s0021-9258(19)86563-8] [Citation(s) in RCA: 23] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022] Open
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23
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Abstract
The current status of knowledge of the major proteins of milks of various species is evaluated. Most of the non-bovine milk proteins are homologous with the recognized families of those of Bos taurus, alpha S1-caseins, alpha S2-caseins, beta-caseins, kappa-caseins, beta-lactoglobulins, and alpha-lactalbumins, each family representing a separate genetic locus specific to the mammary gland. No prominent milk protein not homologous to one of these families has yet been discovered in milk of any species. Genetic polymorphism resulting from substitutions in the polypeptide chains and various degrees of post-translational phosphorylation, glycosylation, and proteolysis have been identified in milk proteins of several species. Total protein production ranges among species from about 0.5 to 10 g/d per kg0.75 maternal weight. Proportions of the several proteins vary greatly among species, but few accurate analytical data are available except for total casein and total whey protein contents.
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24
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Mercier JC, Haze G, Gaye P, Petrissant G, Hue D, Boisnard M. Amino terminal sequence of the precursor of ovine alpha-lactalbumin. Biochem Biophys Res Commun 1978; 85:662-70. [PMID: 736925 DOI: 10.1016/0006-291x(78)91213-5] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
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25
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Kirschenbaum DM. A compilation of amino acid analyses of proteins. XIII. Residues per molecule--10. Anal Biochem 1977; 83:521-50. [PMID: 341745 DOI: 10.1016/0003-2697(77)90057-4] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
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Brown RC, Fish WW, Hudson BG, Ebner KE. Isolation and characterization of rat alpha-lactalbumin: a glycoprotein. BIOCHIMICA ET BIOPHYSICA ACTA 1977; 491:82-92. [PMID: 849470 DOI: 10.1016/0005-2795(77)90043-5] [Citation(s) in RCA: 31] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
Abstract
alpha-Lactalbumin was purified to homogeneity from rat milk. Rat alpha-lactalbumin, in contrast to other alpha-lactalbumins, is a glycoprotein and exhibits an abnormally high molecular weight when obtained by gel filtration or electrophoresis in sodium dodecyl sulfate. The molecular weight by sedimentation equilibrium is 15 400 +/- 5% and of the reduced and alkylated protein is 16 000 when determined by thin-layer chromatography in 6 M guanidine hydrochloride. At least, three major charge forms, all containing carbohydrate and active in the lactose synthetase reaction were demonstrated. The amino acid composition reveals a high proline content which is reflected in a low alpha-helical content.
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27
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Prieels JP, Schlusselberg J. Heterogeneity in alpha-lactalbumins. I. Human alpha-lactalbumin. BIOCHIMICA ET BIOPHYSICA ACTA 1977; 491:76-81. [PMID: 14703 DOI: 10.1016/0005-2795(77)90042-3] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
alpha-Lactalbumin from human milk shows an heterogeneous behaviour when subjected to ion exchange chromatography with DEAE-Sephadex. Two components have been separated, showing identical patterns in the following studies: amino acid compositions, fluorescence and circular dichroism spectra, transition temperature of denaturation, antigenicity, lactose synthase specifying activity and hydrodynamic properties. After rechromatography of either peak, these two components appeared to be in equilibrium. This equilibrium varies with the temperature and the pH of chromatography. Moreover, an increase of n-alcohol concentration in the eluting buffer also induces an increase of the second protein peak eluting at higher ionic strength. These two peaks seem to be the result of some conformational change induced upon the binding of the protein to the solid anionic matrix.
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28
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Whitney RM, Brunner JR, Ebner KE, Farrell HM, Josephson RV, Morr CV, Swaisgood HE. Nomemclature of the proteins of cow's milk: fourth revision. J Dairy Sci 1976; 59:795-815. [PMID: 57970 DOI: 10.3168/jds.s0022-0302(76)84280-4] [Citation(s) in RCA: 161] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
This report reviews the nomenclature of the milk proteins of cow's milk in light of more recent advances in our knowledge. With the establishment of the primary structures of a number of these proteins, we now have a definite identification of alphas1-, kappa-, beta-, and the gamma-caseins as well as beta-lactoglobulin and alpha-lactalbumin. On the basis of new information on their primary structures and relationship to beta-casein polymorphs, changes in nomenclature have been recommended for proteins of the gamma-casein fraction. Although the primary structure serves as the unambiguous definition of proteins for which it is known, a more practical identification is necessary. We recommend that their behavior in gel electrophoresis under suitable conditions be employed for this purpose for all of the "major" milk proteins of raw skim milk except the immunoglobulins where, because of their heterogeneity and molecular genetics, physical parameters are less useful and their identification must be based upon antigenic determinants and their homology with their human counterparts. More work is needed and, with the accumulation of more information, additional changes in nomenclature can be expected for such proteins as the minor components of alphas- and kappa-caseins, alpha-lactalbumin, and the proteose-peptone fraction as well as further confirmation of the presence of immunoglobulins IgE and additional IgG subclasses. Additional components and genetic variants also can be expected.
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29
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Gielens C, Préaux G, Lontie R. Limited trypsinolysis of beta-haemocyanin of Helix pomatia. Characterization of the fragments and heterogeneity of the copper groups by circular dichroism. EUROPEAN JOURNAL OF BIOCHEMISTRY 1975; 60:271-80. [PMID: 1204641 DOI: 10.1111/j.1432-1033.1975.tb21000.x] [Citation(s) in RCA: 35] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/26/2022]
Abstract
A limited trypsinolysis of the tenths of beta-haemocyanin of Helix pomatia was performed at pH 8.2. The absorbance at 346 nm remained constant, indicating a preservation of the oxygen-binding sites. The five tryptic fragments were separated by chromatography on Sephadex G-100 and on DEAE-cellulose. They contained 2 Cu per 50000 daltons and showed different mobilities in agar electrophoresis. The molecular weights indicated that one fragment was constituted of three functional domains of about 50000 daltons, that two fragments were constituted of two domains, and two others of one domain. Twentieths of beta-haemocyanin seemed thus to be made up of 9 domains. The circular dichroic spectra of the fragments indicated the presence of two classes of copper groups according to their positive maximum at 455 or at 500 nm. The circular dichroic spectra also showed that no fragment could have originated from a larger one, confirming the presence of nine domains in the twentieths.
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30
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Miller JN, King LA. The low-temperature luminescence properties of bovine alpha-lactalbumin. BIOCHIMICA ET BIOPHYSICA ACTA 1975; 393:435-45. [PMID: 238614 DOI: 10.1016/0005-2795(75)90072-0] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
The luminescence of bovine alpha-lactalbumin at 77 K has been studied and compared with that of lysozyme. Alpha-Lactalbumin has several unusual properties, including a fluorescence spectrum showing vibrational fine structure, an abnormal phosphorescence spectrum, a high fluorescence: phosphorescence ratio and an abnormal phosphorescence decay. These properties are largely due to the proximity of tryptophan residues to disulphide bonds. Reduction of all these bonds causes considerable changes in alpha-lactalbumin luminescence, as does denaturation in acid solution. Reduction of a single labile disulphide bond has little effect, and the properties of alpha-lactalbumin III, a variant lacking one disulphide bond and one trypotophan residue, are similar to those of the normal protein. Several differences between alpha-lactalbumin and lysozyme are reported. The results support the suggestion that the two tryptophan residues found in the active site cleft of alpha-lactalbumin may be largely responsible for its luminescence.
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Quarfoth GJ, Jenness R. Isolation, composition and functional properties of alpha-lactalbumins from several species. BIOCHIMICA ET BIOPHYSICA ACTA 1975; 379:476-87. [PMID: 1122299 DOI: 10.1016/0005-2795(75)90154-3] [Citation(s) in RCA: 31] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/25/2022]
Abstract
1. Galactosyltranferases were isolated from bovine and pig milk and alpha-labtalbumins from milks of cow, pig, dog, rabbit, baboon and chimpanzee. 2. Alpha-Lactalbumins were characterized by gel electrophoresis, amino acid composition, ultraviolet absorbance, and ability to promote synthesis of lactose by the galactosyltransferases. 3. The order of K-m values of the various alpha-lactalbumins was the same with both cow and pig galactosyltransferases and differed from the order predicted from taxonomical classification of the species. 4. A280/A260 abosrbance ratios were correlated with K-m values suggesting involvement of tyrosyl groups in the function of alpha-lactalbumin.
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Barel AO, Prieels JP. Fluorimetric study of conformational changes of various alpha-lactalbumins on agarose carriers. EUROPEAN JOURNAL OF BIOCHEMISTRY 1975; 50:463-73. [PMID: 236187 DOI: 10.1111/j.1432-1033.1975.tb09824.x] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
1. Various insoluble alpha-lactalbumins (bovine, bovine glyco-alpha-lactalbumin, human and human nitrated) have been prepared by coupling these proteins on to an agarose gel with use of cyanogen bromide. 2. Some intrinsic fluorescence properties, such as fluorescence maximum and pH dependence, were considered in order to study conformational changes of the alpha-lactalbumins covalently bound to an insoluble matrix. Examination of the pH-fluorescence profiles as well as the position of the maximum in the emission spectrum indicates that the Sepharose matrix does not appreciably modify the conformation of human and bovine glyco-alpha-lactalbumins. Some changes in the fluorescence spectrum (peak shifting towards longer wavelength) was observed for bovine alpha-lactalbumin and appeared to be due to alteration of the environment of the tryptophan side-chains in the protein upon coupling to the agarose gel. The emission spectrum of the insolubilized human nitrated alpha-lactalbumin indicates that the polypeptide chain of this protein gained some native conformation when covalently bound to the carrier. 3. The extrinsic fluorescence of a bound dye, such as 2-p-toluidinylnaphthalene-6-sulfonate, was used to study and to compare the hydrophobic sites on the surface of insoluble alpha-lactalbumins with the same proteins in solution. Considering the fluorescence properties of the protein with dye complexes it was found that both states of alpha-lactalbumins (insoluble and free in solution) bind the dye with similar association constants. However, the positions of the maxima in the emission spectra are all somewhat shifted towards longer wavelengths, suggesting that the dye binding site is located in a more polar environment when the proteins are bound to agarose. The human nitrated alpha-lactalbumin retains about equal possibility of binding this fluorescent dye. 4. As shown for bovine alpha-lactalbumin in solution, the binding of 2-p-toluidinylnaphthalene-6-sulfonate towards the various insoluble alpha-lactalbumins was not appreciably modified by the presence of various small compounds such as sugars and UDP, which are effectors in the lactose synthetase function.
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Ljungquist A, Lindqvist LO, Wallin P. Fractionation of some bovine whey proteins by recycling gel filtration on a large scale. PREPARATIVE BIOCHEMISTRY 1975; 5:131-46. [PMID: 1170559 DOI: 10.1080/00327487508061566] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/25/2022]
Abstract
Fractionation of bovine whey concentrate was performed by gel filtration on Sephadex G-75 both on a laboratory scale and on a large scale. By a recycling procedure and improved separation was obtained and the whey proteins were resolved into four fractions in the weight ratio 3:12:1:4. The fractions were analysed by polyacrylamide gel (PAG) electrophoresis and the apparent molecular weights were determined by thin layer gel chromatography (TLG) and by sodium dodecylsulfate (SDS) gel electrophoresis.
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Davies DT. The quantitative partition of the albumin fraction of milk serum proteins by gel chromatography. J DAIRY RES 1974; 41:217-28. [PMID: 4135090 DOI: 10.1017/s0022029900019634] [Citation(s) in RCA: 23] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023]
Abstract
SummaryA method for the quantitative partition of the albumin fraction of milk serum proteins is described. The partition, which is carried out by chromatography on a column of Sephadex G-100 (2·5×90cm) at 4°C in the presence of 0·02 m-sodium phosphate buffer (pH 6·7) containing 0·1 m-NaCl, yields 4 fractions. By gel electrophoresis it was shown that the fractions represent, in order of elution from the Sephadex, the following: fraction 1, a mixture of the largest proteins present, probably comprising γ-globulins, proteose-peptones and lactoferrin; fraction 2, bovine serum albumin and bovine serum transferrins; fraction 3, β-lactoglobulins; and fraction 4, α-lactalbumins. The protein contents of the various fractions were determined by nitrogen analysis and the results showed that good agreement was obtained between values from duplicate fractionations, and also that the recovery of material was satisfactory. The partition of the albumin fraction was not complete, but at least 90% of the material was found in fractions which represent essentially single proteins. The influences of some aspects of the pretreatment of samples, buffer composition and column preparation are described.
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Hopper KE, McKenzie HA. Comparative studies of alpha-lactalbumin and lysozyme: Echidna lysozyme. Mol Cell Biochem 1974; 3:93-108. [PMID: 4208938 DOI: 10.1007/bf01659181] [Citation(s) in RCA: 37] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023]
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Barman TE. The isolation of an -lactalbumin with three disulphide bonds. EUROPEAN JOURNAL OF BIOCHEMISTRY 1973; 37:86-9. [PMID: 4738094 DOI: 10.1111/j.1432-1033.1973.tb02960.x] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/12/2023]
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Hopper KE. Apparent heterogeneity of bovine -lactalbumin A and B in DEAE-Sephadex chromatography. BIOCHIMICA ET BIOPHYSICA ACTA 1973; 295:364-70. [PMID: 4630930 DOI: 10.1016/0005-2795(73)90103-7] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/11/2023]
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