Concentration difference spectra in the dimerization of insulin

Rupley, John A.; Renthal, Robert; Praissman, Melvin

doi:10.1016/0005-2795(67)90397-2

Cited by 34 publications

(19 citation statements)

References 8 publications

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“…difference spectra give information about the interaction between the ligand and the chromophoric side chains of the protein. The changes in the spectra measured between 260 and 300nm are consistent with the perturbation of the tyrosine residues (Rupley et al, 1967;Steinhardt & Reynolds, 1969;Steiner & Weinryb, 1971) arising from the detergent binding. The difference spectra given in Fig.…”

Section: Fig I Precipitation Of Insulin By Cetyltrinmethylammonium supporting

confidence: 59%

“…2 suggest that the environment of the tyrosine changes to a more apolar character after detergent binding. It has been reported that in solution, when the insulin molecule is in the associated state (dimer or tetramer), the chromophoric side chains interact (Rupley et al, 1967). It has also been shown that in the solid state an aromatic cage consisting of tyrosine and phenylalanine residues is present in the insulin dimer (Blundell et al, 1971).…”

Section: Fig I Precipitation Of Insulin By Cetyltrinmethylammonium mentioning

confidence: 99%

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The binding of cationic detergent to insulin, zinc–insulin and iso-insulin (Short Communication)

Birdi

1973

Biochemical Journal

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Insulin, zinc-insulin and iso-insulin were precipitated by cetyltrimethylammonium bromide when the detergent/protein molar ratio was less than 10:1, whereas no precipitation was observed at ratios greater than 10:1. It is concluded that the detergent binds as a dimer at each binding site at ratios greater than 10:1. U.v. difference spectra indicated that the tyrosine residues were perturbed by detergent binding.

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Section: Fig I Precipitation Of Insulin By Cetyltrinmethylammonium supporting

confidence: 59%

Section: Fig I Precipitation Of Insulin By Cetyltrinmethylammonium mentioning

confidence: 99%

The binding of cationic detergent to insulin, zinc–insulin and iso-insulin (Short Communication)

Birdi

1973

Biochemical Journal

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“…Insulin was injected at two concentration levels of 4.3 or 57.3 μmol L –1 . Given the range of estimates for the dimerization constant depending on pH and ionic strength found in the literature, ,− we expect the insulin, in the absence of divalent ions, to be mainly monomeric at 4.3 μmol L –1 and to be mainly dimeric at 57.3 μmol L –1 . The mobility of insulin at the latter concentration tends to be slightly higher than that at the former one, which may be caused by a stronger tendency for dimerization at higher protein concentration.…”

Section: Resultsmentioning

confidence: 95%

Binding of Divalent Cations to Insulin: Capillary Electrophoresis and Molecular Simulations

et al. 2018

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In the present study, we characterize the binding of divalent cations to insulin in aqueous salt solutions by means of capillary electrophoresis and molecular dynamics simulations. The results show a strong pH dependence. At low pH, at which all the carboxylate groups are protonated and the protein has an overall positive charge, all the cations exhibit only weak and rather unspecific interactions with insulin. In contrast, at close to neutral pH, when all the carboxylate groups are deprotonated and negatively charged, the charge-neutralizing effect of magnesium, calcium, and zinc, in particular, on the electrophoretic mobility of insulin is significant. This is also reflected in the results of molecular dynamics simulations showing accumulation of cations at the protein surface, which becomes smaller in magnitude upon effective inclusion of electronic polarization via charge rescaling.

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“…Although insulin exhibits a strong propensity for selfassociation, at pH 2 and at physiologic concentrations the predominant form may well be monomeric. [40][41][42] It is notable that the insulin molecule can retain transport and antilipolytic activities while coupled to a large polymer which apparently cannot enter the cell. It is perhaps surprising that the particles, which may be even larger than the fat cells, did not restrict more severely the proper interaction of insulin with the cell surface.…”

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confidence: 99%

Interaction of Insulin With the Cell Membrane: The Primary Action of Insulin

Cuatrecasas

1969

Proc. Natl. Acad. Sci. U.S.A.

354

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Abstract.-Insulin can be covalently attached to large polymers of Sepharose through the a-amino group of the N-terminal residue of the B chain, or through the e-amino group of its lysyl residue. Such derivatives effectively increase the utilization of glucose, and suppress the hormone-stimulated lipolysis, of isolated fat cells. The effects occur with concentrations of insulin-Sepharose that are nearly as low as those of native insulin, and the maximal responses are the same. The results indicate that interaction of insulin with superficial membrane structures alone may suffice to initiate transport as well as other metabolic alterations.Insulin facilitates transmembrane sugar transport in adipose tissue and muscle, and it can promote other transport processes (i.e., amino acids,1' 2 K+ 3) in the absence of glucose. The hormone also modifies cellular processes through mechanisms which are probably independent of its transport function.4 Insulin can antagonize hormone-stimulated lipolysis,5-8 as well as increase the incorporation of amino acids into protein,9-12 in the absence of medium glucose. Furthermore, the effects of insulin on the cyclic AMP of adipose tissue,13 14 glycogen phosphorylase, and glycogen synthetase,13 also appear to be independent of alterations of transport processes.It is not known whether insulin exerts any or all of its metabolic effects solely by interacting with surface membrane structures, or by entrance of the protein (or portion thereof) into the cell. Although the "binding" of insulin to various tissues has been extensively studied,15-25 these studies do not discriminate among "binding" of insulin to intracellular, membrane, and connective tissue structures.In the present studies polymeric insulin derivatives were prepared by selectively linking insulin through phenylalanine B1, or lysine B29, to large agarose polymers (Sepharose, particle size 60-300 ,j). The techniques used were similar to those described for the preparation of derivatives for affinity-chromatography purification of various enzymes26 and avidin.27 The biological integrity of these covalently bound insulin derivatives was established by measuring their effects on glucose transport and lipolysis of isolated fat cells (cell size, 50-100 ).28 Since the derivatives do not appear to enter the fat cells, and since proteolytic cleavage of the bound insulin molecule probably cannot result in active peptide fragments, the results reported here indicate that interaction of insulin with cell surface structures is sufficient to initiate a variety of metabolic alterations.Preparation of Insulin-Sepharose Derivatives.-Crystalline pork zinc-insulin was coupled to Sepharose which had been activated with CNBr by slight modifications of procedures previously described (Table 1) I These were used for studies of biological and immunochemical properties.31 § The N-terminal amino acid residues of insulin had been previously acetylated.0.2 M NaHCO3, pH 8.6, over 1 hr; gentle stirring for 20 hr in 2 liters of 0.4 M NaHCO3, pH 8.6; 6 liter...

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Concentration difference spectra in the dimerization of insulin

Cited by 34 publications

References 8 publications

The binding of cationic detergent to insulin, zinc–insulin and iso-insulin (Short Communication)

The binding of cationic detergent to insulin, zinc–insulin and iso-insulin (Short Communication)

Binding of Divalent Cations to Insulin: Capillary Electrophoresis and Molecular Simulations

Interaction of Insulin With the Cell Membrane: The Primary Action of Insulin

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