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Hahn DK, Aragon SR. Intrinsic Viscosity of Proteins and Platonic Solids by Boundary Element Methods. J Chem Theory Comput 2015; 2:1416-28. [PMID: 26626849 DOI: 10.1021/ct600062y] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
The boundary element (BE) method is used to implement a very precise computation of the intrinsic viscosity for rigid molecules of arbitrary shape. The formulation, included in our program BEST, is tested against the analytical Simha formula for ellipsoids of revolution, and the results are essentially numerically exact. Previously unavailable, very precise results for a series of Platonic solids are also presented. The formulation includes the optional determination of the center of viscosity; however, for globular proteins, the difference compared to the computation based on the centroid is insignificant. The main application is to a series of 30 proteins ranging in molecular weight from 12 to 465 kD. The computation starts from the crystal structure as obtained from the Protein Data Bank, and a hydration thickness of 1.1 Å obtained in previous work with BEST was used. The results (extrapolated to an infinite number of triangular boundary elements) for the proteins are separated into two groups: monomeric and multimeric proteins. The agreement with experimental measurements of the intrinsic viscosity in the case of monomeric proteins is excellent and within experimental error of 5%, demonstrating that the solution and crystal structure are hydrodynamically equivalent. However, for some multimeric proteins, we observe strong systematic deviations around -20%, which we interpret as a systematic deviation of the solution structure from the crystal structure. A possible description of the structural change is deduced by using simple ellipsoid model parameters. A method to obtain intrinsic viscosity values for proteins to 1-2% accuracy (better than experimental error) on the basis of a single BE computation (avoiding the need for an extrapolation on the number of surface triangles) is also presented.
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Affiliation(s)
- David K Hahn
- Department of Chemistry and Biochemistry, San Francisco State University, 1600 Holloway Ave., San Francisco, California 94132
| | - Sergio R Aragon
- Department of Chemistry and Biochemistry, San Francisco State University, 1600 Holloway Ave., San Francisco, California 94132
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Liu F, Kohn WD, Mayer JP. Site-specific fluorescein labeling of human insulin. J Pept Sci 2012; 18:336-41. [PMID: 22492582 DOI: 10.1002/psc.2405] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/25/2012] [Accepted: 01/27/2012] [Indexed: 11/11/2022]
Abstract
Three fluorescein derivatives of human insulin (HI, 1) labeled at positions N(αA1) , N(αB1) and N(εB29) respectively, were synthesized using an N-trifluoroacetyl-based protecting group scheme. The Tfa protecting group introduced by reaction with ethyl trifluoroacetate was found to be stable in aqueous and organic media and efficiently removed under mild basic conditions.
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Affiliation(s)
- Fa Liu
- Lilly Research Laboratories, Indianapolis, IN 46285, USA
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Tsai YJ, Rottero A, Chow DD, Hwang KJ, Lee VH, Zhu G, Chan KK. Synthesis and purification of NB1-palmitoyl insulin. J Pharm Sci 1997; 86:1264-8. [PMID: 9383737 DOI: 10.1021/js9701263] [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: 02/05/2023]
Abstract
A procedure for synthesizing NB1-palmitoyl insulin for incorporation into liposomes for targeting to hepatocytes was developed. The amino group of the first amino acid phenylalanine on the B chain (B1) of insulin was selected for conjugation with palmitic acid in anticipation that its binding to the insulin receptor would be preserved. Two other free amino groups present in insulin, the first amino acid glycine on the A chain (A1) and the 29th amino acid lysine on the B chain (B29), were first protected with a t-butoxycarbonyloxy (t-Boc) group to yield NA1, B29-di-(t-Boc) insulin. The identity of this di-(t-Boc) insulin was confirmed by amino acid analysis as well as by enzyme hydrolysis coupled with matrix-assisted laser-desorption time of flight mass spectrometry (MALDI-TOF MS). NA1,B29-Di-(t-Boc) insulin was then reacted with the N-hydroxysuccinimide ester of palmitic acid, followed by deblocking the t-Boc groups, to yield NB1-palmitoyl insulin, the structure of which was further confirmed by MALDI-TOF MS analysis. NB1-palmitoyl insulin was found to interact with the insulin receptor on fat cells, thereby catalyzing the conversion of [14C]glucose into lipids, at reduced efficiency (30-40%).
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Affiliation(s)
- Y J Tsai
- Department of Pharmaceutical Sciences, School of Pharmacy, University of Southern California, Los Angeles 90033, USA
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Brown LR, Edelman ER, Fischel-Ghodsian F, Langer R. Characterization of glucose-mediated insulin release from implantable polymers. J Pharm Sci 1996; 85:1341-5. [PMID: 8961150 DOI: 10.1021/js9600686] [Citation(s) in RCA: 46] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/03/2023]
Abstract
We characterized a glucose-sensitive, controlled-release insulin delivery system. Insulin release rates increased when glucose was perfused in the release media surrounding the matrix. The system was composed of solid, particulate insulin, incorporated into an ethylene-vinyl acetate copolymer (EVAc) matrix. Feedback control was mediated by the glucose oxidase enzyme immobilized to Sepharose beads, which were incorporated along with insulin into the EVAc matrix. When glucose in solution entered the insulin delivery system, gluconic acid was produced, causing a drop in the microenvironmental pH of the matrix. This fall in pH resulted in a rise in insulin solubility and consequently a rise in the insulin release rate from the matrix. Insulin concentrations increased in vitro and in vivo in response to glucose infusion. The increased insulin release was shown to consist of a finite pulse of insulin that required an optimal recovery period of 1 h to achieve a maximal repeated response to a glucose stimulus. Repeated pulses were demonstrated over a 4 h period. An optimum enzyme ratio was also determined.
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Affiliation(s)
- L R Brown
- Division of Health Sciences and Technology, Massachusetts Institute of Technology, Cambridge 02139, USA
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Affiliation(s)
- R Langer
- Department of Chemical Engineering Massachusetts Institute of Technology, Cambridge 02139
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Fischel-Ghodsian F, Brown L, Mathiowitz E, Brandenburg D, Langer R. Enzymatically controlled drug delivery. Proc Natl Acad Sci U S A 1988; 85:2403-6. [PMID: 3281165 PMCID: PMC280001 DOI: 10.1073/pnas.85.7.2403] [Citation(s) in RCA: 106] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/05/2023] Open
Abstract
An approach for providing feedback control for polypeptide drugs in a polymeric controlled-release system uses a trigger molecule and a polymer-bound enzyme that, in the presence of that trigger molecule, will cause an acid or a base to form. When the pH inside the polymer system changes, the solubility of the drug shifts dramatically, which changes the diffusion or dissolution driving force, and hence the release rate changes correspondingly. This concept was tested using a controlled-release system of ethylene/vinyl acetate copolymer containing insulin and immobilized glucose oxidase. The enzymatic reaction of glucose to gluconic acid reduces the pH in the polymer microenvironment. Since insulin solubility increases with decreasing pH (at physiologic pH, this is true for an insulin with an isoelectric point of 7.4 or higher), the release of insulin increases in response to glucose concentration. The feasibility of this concept has been shown using trilysyl insulin with an isoelectric point of 7.4. Multiple exposures to buffered glucose solutions over several weeks caused insulin release to reversibly increase during each exposure. Polymer-implanted diabetic rats infused with glucose solutions showed a significant increase in insulin concentration in 30 min-an effect not observed in three different sets of control rats.
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Affiliation(s)
- F Fischel-Ghodsian
- Massachusetts Institute of Technology, Department of Applied Biological Sciences, Cambridge, 02139
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8
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Canova-Davis E, Carpenter FH. Semisynthesis of insulin: specific activation of the arginine carboxyl group of the B chain of desoctapeptide-(B23--30)-insulin (bovine). Biochemistry 1981; 20:7053-8. [PMID: 7032587 DOI: 10.1021/bi00527a044] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/23/2023]
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9
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Inouye K, Watanabe K, Tochino Y, Kanaya T, Kobayashi M, Shigeta Y. Semisynthesis and biological properties of the [B24-leucine]-, [B25-leucine[- and [B24-leucine, B25-leucine]-analogues of human insulin. EXPERIENTIA 1981; 37:811-3. [PMID: 7026270 DOI: 10.1007/bf01985653] [Citation(s) in RCA: 18] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/23/2023]
Abstract
Trypsin-catalyzed coupling of porcine desoctapeptide-insulin with synthetic octapeptides produced the [LeuB24]- (I), [LeuB25]- (II) and [LeuB24, LeuB25]- (III)analogues of human insulin. I, II and III displayed respectively 20--30%, 1--2% and 0.5% of the receptor binding activity of the normal hormone. Biological activities of these analogues seemed to be proportional to their binding potencies when assayed in vitro, while in an in vivo assay analogue I was fully active and II exhibited 10--20% of normal activity. III was less active than II in all assays tested.
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Tager H, Thomas N, Assoian R, Rubenstein A, Saekow M, Olefsky J, Kaiser ET. Semisynthesis and biological activity of porcine [LeuB24]insulin and [LeuB25]insulin. Proc Natl Acad Sci U S A 1980; 77:3181-5. [PMID: 6997872 PMCID: PMC349578 DOI: 10.1073/pnas.77.6.3181] [Citation(s) in RCA: 65] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/22/2023] Open
Abstract
Two analogs of porcine insulin with substitutions of leucine for phenylalanine in the COOH-terminal region of the insulin B chain have been prepared by a combination of solid-phase synthesis and semisynthesis. Solid-phase synthesis of the substituted octapeptides B23-B30 bearing the trifluoracetyl group on lysine-B29, enzymatic coupling of the octapeptides to bis(tertiary-butyloxycarbonyl)desoctapeptide insulin by trypsin, and deprotection of the corresponding adducts in formic acid and piperidine resulted in two insulin derivatives, one with leucine at position B24 and the other with leucine at position B25. These analogs had only about 10% and 1%, respectively, of the activity of porcine insulin in competing for the binding of [125I]iodoinsulin to both rat adipocytes and human IM-9 lymphocytes. The relative potencies of the analogs in stimulating glucose oxidation by rat adipocytes decreased in the order porcine insulin > [LeuB24]insulin > [LeuB25]insulin. However, at high concentrations both analogs had full agonists activity. Experiments in which the semisynthetic insulins were mixed with the native hormone showed that [LeuB24]insulin, but not [LeuB25]insulin, was an active antagonist of insulin action. These results suggest that the antagonistic activity of a human insulin variant having leucine at position B24 or B25 can be assigned to the molecule with the sequence Gly-Leu-Phe-Tyr (residues B23-B26) in its active site.
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11
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Yip C, Yeung C, Moule M. Photoaffinity labeling of insulin receptor of rat adiopocyte plasma membrane. J Biol Chem 1978. [DOI: 10.1016/s0021-9258(19)62315-x] [Citation(s) in RCA: 165] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022] Open
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12
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Dostál J, Havránek M, Matousek J, Stanĕk R, Linhart J. Substitution of ribonuclease in relation to its activity. THE INTERNATIONAL JOURNAL OF BIOCHEMISTRY 1978; 9:667-80. [PMID: 361468 DOI: 10.1016/0020-711x(78)90094-0] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
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13
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Lode ET, Murray CL, Rabinowitz JC. Derivatives of Clostridium acidi-urici ferredoxin containing altered amino acid sequences. Semisynthetic synthesis, biological activity, and stability. J Biol Chem 1976. [DOI: 10.1016/s0021-9258(17)33702-x] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022] Open
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14
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Lode ET, Murray CL, Sweeney WV, Rabinowitz JC. Synthesis and properties of Clostridium acidi-urici (Leu2)-ferredoxin: a function of the peptide chain and evidence against the direct role of the aromatic residues in electron transfer. Proc Natl Acad Sci U S A 1974; 71:1361-5. [PMID: 4364535 PMCID: PMC388228 DOI: 10.1073/pnas.71.4.1361] [Citation(s) in RCA: 26] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/10/2023] Open
Abstract
Tyrosyl or other aromatic residues generally occur in two conserved positions in the peptide chain of clostridial-type ferredoxins and have been implicated in the electron transfer function of these iron-sulfur proteins. We have prepared and determined some of the properties of a derivative of Clostridium acidi-urici ferredoxin, [Leu(2)]-ferredoxin, in which a leucyl residue has been substituted for the tyrosyl residue in position 2 from the amino terminus. [Leu(2)]-ferredoxin is fully active as an electron carrier in two biological assays, the phosphoroclastic enzyme system and the ferredoxin-dependent reduction of cytochrome c in the presence of ferredoxin-TPN reductase and TPNH. Quantitative electron paramagnetic resonance experiments indicate that [Leu(2)]-ferredoxin accepts nearly two electrons upon enzymatic reduction by pyruvate-ferredoxin oxidoreductase and an excess of pyruvate. If electron transfer to an iron-sulfur cluster is the rate-limiting step in the assays used, and if the rate of electron transfer through Tyr(30) is not much faster than through Tyr(2), these results indicate that the primary pathway of electron transfer in clostridial-type ferredoxins is not via Tyr or other aromatic amino-acid residues. The syntheses of other ferredoxin derivatives with amino-acid substitutions or deletions in positions 1 and 2 indicate that a large bulky residue, but not necessarily an aromatic residue, is needed in position 2 for the stability of this ferredoxin. The residue in position 2, therefore, appears to act as a hydrophobic shield for an iron-sulfur cluster.
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15
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Levy D. The synthesis of several tert-butyloxycarbonyl derivatives of insulin. BIOCHIMICA ET BIOPHYSICA ACTA 1973; 328:107-13. [PMID: 4761986 DOI: 10.1016/0005-2795(73)90336-x] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/12/2023]
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16
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Wachter E, Machleidt W, Hofner H, Otto J. Aminopropyl glass and its p-phenylene diisothiocyanate derivative, a new support in solid-phase Edman degradation of peptides and proteins. FEBS Lett 1973; 35:97-102. [PMID: 4356495 DOI: 10.1016/0014-5793(73)80585-x] [Citation(s) in RCA: 146] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/10/2023]
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17
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Hollands TR, Youson JH. A source of error in the rat diaphragm assay of insulin. Anal Biochem 1973; 54:413-8. [PMID: 4724546 DOI: 10.1016/0003-2697(73)90370-9] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/12/2023]
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18
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Levy D. The esterification of insulin with triethyloxonium tetrafluoroborate. BIOCHIMICA ET BIOPHYSICA ACTA 1973; 310:406-15. [PMID: 4719150 DOI: 10.1016/0005-2795(73)90122-0] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/12/2023]
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19
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Havránek M, Vereš K. A convenient method for preparation of14C-labelled basic nuclear protein - histone. ACTA ACUST UNITED AC 1972. [DOI: 10.1002/jlcr.2590080420] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
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Abstract
Human insulin differs from porcine insulin by a single amino acid- the carboxyl terminal residue of the B chain. By means of chemical and enzymatic treatment, it is possible to remove quantitatively and selectively the carboxyl terminal octapeptide from porcine insulin B chain. This fragment can be replaced by an analogous synthetic human octapeptide to give a protein which is identical to human insulin by a number of criteria. By this method, human insulin can be prepared on a large scale simply and inexpensively from porcine insulin. The method is also useful for preparing specifically labeled radioactive human insulin, as well as insulins with modified amino acid sequences, for research purposes.
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Affiliation(s)
- D G. Lindsay
- Department of Biochemistry, School of Biological Sciences, University of Sussex, Falmer, Brighton BN1 9QG, Sussex, UK
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Laursen RA, Horn MJ, Bonner AG. Solid-phase Edman degradation. The use of p-phenyl diisothiocyanate to attach lysine- and arginine-containing peptides to insoluble resins. FEBS Lett 1972; 21:67-70. [PMID: 11946477 DOI: 10.1016/0014-5793(72)80165-0] [Citation(s) in RCA: 120] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Affiliation(s)
- R A. Laursen
- Max-Planck Institut für Molekulare Genetik, Berlin-Dahlem, Germany
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24
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Laursen RA. [27] Automatic solid-phase Edman degradation. Methods Enzymol 1972; 25:344-59. [DOI: 10.1016/s0076-6879(72)25030-3] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 03/07/2023]
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25
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Brandenburg D, Gattner HG, Herbertz L, Krail G, Weinert M, Zahn H. Semisynthetic insulin analogues. Biochem J 1971; 125:51P-52P. [PMID: 5169434 PMCID: PMC1178204 DOI: 10.1042/bj1250051p] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/14/2023]
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27
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Katsoyannis PG, Zalut C, Harris A, Meyer RJ. Analogs of insulin. 1. Synthesis of destripeptide B 28-30 bovine insulin and destripeptide B 28-30 porcine (human) insulin. Biochemistry 1971; 10:3884-9. [PMID: 5160415 DOI: 10.1021/bi00797a014] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/14/2023]
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28
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Laursen RA. Solid-phase Edman degradation. An automatic peptide sequencer. EUROPEAN JOURNAL OF BIOCHEMISTRY 1971; 20:89-102. [PMID: 5578618 DOI: 10.1111/j.1432-1033.1971.tb01366.x] [Citation(s) in RCA: 318] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/15/2023]
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Rosmus J, Deyl Z. [Chromatographic methods in the analysis of protein structure. The methods for identification of N-terminal amino acids in peptides and proteins. A]. CHROMATOGRAPHIC REVIEWS 1971; 13:163-302. [PMID: 4930151 DOI: 10.1016/0009-5907(71)80001-7] [Citation(s) in RCA: 35] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/13/2023]
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30
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Abstract
The acetylation of the free amino groups of insulin was studied by reaction of the hormone with N-hydroxysuccinimide acetate at pH6.9 and 8.5. The products formed were separated by chromatography on DEAE-Sephadex and were characterized by isoelectric focusing, by end-group analysis, by the incorporation of [(3)H]acetyl groups in the molecule, and by treatment with trypsin that had been treated with 1-chloro-4-phenyl-3-toluene-p-sulphonamidobutan-2-one (;tosylphenylalanyl chloromethyl ketone'). Three monosubstituted products, two disubstituted products and one trisubstituted derivative were prepared. The alpha-amino groups of the terminal residues and the in-amino group of the lysine-B29 were the sites of reaction. Acetylation of any of the free amino groups did not affect the biological activity of insulin. It was demonstrated, however, that substitution at the glycine-A1 amino group by the larger residues, acetoacetyl or thiazolidinecarbonyl, produced a decrease in biological activity. Modification of the lysine-B29 or phenylalanine-B1 amino groups with these larger reagents did not affect the biological activity. Modification of the phenylalanine-B1 amino group by any of the three substituents resulted in a large decrease in the affinity of insulin for anti-insulin antibodies raised in the guinea pig. Modification of the other two amino groups did not affect the reaction with antibody. These observations are correlated with the tertiary structure of insulin.
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31
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Hong JS, Rabinowitz JC. The Effects of Chemical Modifications on the Reconstitution, Activity, and Stability of Clostridial Ferredoxin. J Biol Chem 1970. [DOI: 10.1016/s0021-9258(18)62806-6] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022] Open
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32
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Lindsay DG, Shall S. Monosubstituted 2,2-dimethyl-3-formyl-L-thiazolidine-4-carbonyl-insulins. EUROPEAN JOURNAL OF BIOCHEMISTRY 1970; 15:547-54. [PMID: 5455666 DOI: 10.1111/j.1432-1033.1970.tb01039.x] [Citation(s) in RCA: 19] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/15/2023]
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33
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Stark GR. Recent developments in chemical modification and sequential degradation of proteins. ADVANCES IN PROTEIN CHEMISTRY 1970; 24:261-308. [PMID: 4915249 DOI: 10.1016/s0065-3233(08)60243-0] [Citation(s) in RCA: 67] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/13/2023]
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Abstract
Insulin was treated with diketen at pH6.9. The reaction mixture was resolved into four components by DEAE-Sephadex chromatography. The first component was unchanged insulin. The second and third components were shown by end-group analysis to be substituted on phenylalanine B-1 and glycine A-1 respectively. The fourth component was disubstituted on both phenylalanine B-1 and glycine A-1. The in-amino group of lysine B-29 was not involved in the reaction at low reagent concentrations. The purity of these derivatives was checked by their electrophoretic behaviour and by measurement of the rate of their reaction with trinitrobenzenesulphonic acid. The hormonal activity of the derivatives was determined. The effect of the modifications on the hormonal activity and the tertiary structure of insulin is discussed.
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Bosshard HR, Jorgensen KH, Humbel RE. Preparation and properties of cyanoethylated insulin. An insulin derivative with blocked amino- and imidazole-groups. EUROPEAN JOURNAL OF BIOCHEMISTRY 1969; 9:353-62. [PMID: 4978608 DOI: 10.1111/j.1432-1033.1969.tb00616.x] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/13/2023]
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