Tyrosine A14[125I]monoiodoinsulin: Preparation, Biologic Properties, and long-term stability

Linde, Susanne; Hansen, Bruno; Sonne, Ole; Holst, J. J.; Gliemann, Jørgen

doi:10.2337/diabetes.30.1.1

Cited by 45 publications

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“…Although heavy iodination has long been known to reduce biological potency and metabolic clearance rate of insulin, monoiodination, particularly on Tyr A14, carries little if any deleterious effect, in vitro, insulin monoiodinated on A14 has the same or a slightly higher potency than native insulin [24][25][26]. In vivo, monoiodinated insulin seems to be cleared as fast as native insulin although this is not fully agreed upon [27][28][29][30].…”

Section: Discussionmentioning

confidence: 99%

“…These combined differences account for the fact that liver activity profiles obtained with labelled insulin and des (64, 65) HPI cross each other around the 12th min, As shown in isolated rat fat cells by Podlecki et al HPI and HI are processed with different kinetics [36]. A recent work (Duckworth et al, personal communication) indicates that rat fat cells convert biosynthetic HPI to intermediates cleaved in the region of the B chain (residues [23][24] or of the connecting peptide (residues 55-56) but not to insulin. It is tempting to speculate that slow degradation of internalised material and, proteolytic cleavage without conversion to insulin, also occur in other target tissues and are applicable to HPI conversion intermediates as well as to intact HPI.…”

Section: Discussionmentioning

confidence: 99%

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Scintigraphic distribution of 123 I labelled proinsulin, split conversion intermediates and insulin in rats

et al. 1988

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Summary. Insulin, biosynthetic human proinsulin and 2 human proinsulin conversion intermediates, des (64, 65) human proinsulin and des (31, 32) human proinsulin, were labelled with 123 I and the derivatives monosubstituted on Tyr A14 were purified by reverse phase high performance liquid chromatography. The four tracers were injected into anaesthetized rats via a jugular or a portal vein and time activity curves were generated for the liver and kidneys using a gamma camera and an online computer. Liver extraction coefficients varied in the order insulin (38%), des (64, 65) human proinsulin (11.7%), des (31, 32) human proinsulin (3.2%), human proinsulin (1.6%); whereas half-life of hepatic activity varied in the reverse order, from 6 rain for insulin, to 45 min for human proinsulin. As expected for a non-receptor mediated process, kidney extraction varied conversely to liver extraction, being highest for human proinsulin and lowest for insulin. It is concluded that the kinetics of human proinsulin conversion intermediates depends upon the site of cleavage and deletion and is intermediate between those of insulin and intact human proinsulin.Key words: Biosynthetic human proinsulin, conversion intermediates, 123-I-labelling, scintillation scanning.Most of proinsulin is converted to insulin inside the B cells of the pancreas, a process resulting from the interplay of several endopeptidases, different from trypsin itself [1][2][3]. Recently, two distinct site-specific endopeptidases regulated by calcium concentration and pH were identified in a B granule fraction of rat insulinoma [4]. During proinsulin processing, conversion intermediates are formed, in particular the split products des (64, 65) human proinsulin (HPI) and des (31, 32) HPI. These intermediates and intact HPI have been found in human sera [5], in insulin producing islet cell tumours [6-81 and in familial hyperproinsulinaemia [9-111. Conversion to intermediates or insulin does not seem to occur after proinsulin enters the blood stream; partial conversion to intermediates might occur in the skin after subcutaneous injection [121.From the standpoint of biological activity, proinsulin has remarkable characteristics. Compared to insulin, HPI has a low biological potency, a low avidity for insulin receptors and a prolonged half-life [13][14][15][16][17]. Moreover, the proinsulin conversion intermediates have been shown to exhibit greater biological activity than proinsulin itself, and this is particularly true for the conversion intermediate in which the C peptide/A chain bond has been cleaved. Peavy et al. demonstrated that cleavage and/or dibasic amino acid deletions in the connecting peptide region of proinsulin enhance the receptor binding and hypoglycaemic activities of these compounds. In these studies, C peptide/A chain split products exhibited greater receptor affinity and hypoglycaemic activity than B chain C peptide split intermediates [18]. These observations prompted us to investigate the hepatic extraction and processing of HPI and its conver...

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Section: Discussionmentioning

confidence: 99%

Section: Discussionmentioning

confidence: 99%

Scintigraphic distribution of 123 I labelled proinsulin, split conversion intermediates and insulin in rats

et al. 1988

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“…Serial dilutions of bovine insulin, DPI or DHI were added to the incubation vials containing aliquots of the cell suspension. The radioligand used was 125I insulin prepared by the chloramine T technique using a 10:1 molar ratio of chloramine T to insulin and purified by discontinuous polyacrylamide gel electrophoresis using a modification of the method described by Linde et aL [17]. The material used was obtained from the peak corresponding to Al4-monoiodoinsulin [17].…”

Section: Fat Cell Bindingmentioning

confidence: 99%

“…The radioligand used was 125I insulin prepared by the chloramine T technique using a 10:1 molar ratio of chloramine T to insulin and purified by discontinuous polyacrylamide gel electrophoresis using a modification of the method described by Linde et aL [17]. The material used was obtained from the peak corresponding to Al4-monoiodoinsulin [17]. The incubation period was 60 min at 30~ Bound and free radioligand were then separated by centrifugation after the addition of dinonylphthalate to triplicate 200 ~1 samples of incubation mixture placed in microfuge tubes.…”

Section: Fat Cell Bindingmentioning

confidence: 99%

An examination of the role of insulin dimerisation and negative cooperativity using the biological properties of the despentapeptide and deshexapeptide insulins

et al. 1987

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Summary. The C-terminus of the insulin B chain is essential for dimerisation and expression of negative cooperativity. In order to evaluate the possible physiological role of these phenomena, we have studied the properties in vivo and in vitro of despentapeptide insulin (B26-30 deleted), derived from beef insulin, and deshexapeptide insulin (B25-30 deleted), derived from pork insulin. These materials do not dimerise and have 15% and 0% retention of negative cooperativity respectively. Lipogenesis potencies in rat adipocytes were: despentapeptide insulin 19.9+0.3%; deshexapeptide insulin 19.9 + 1.5%. Binding potencies in adipocytes were: despentapeptide insulin 22.6+7.8%; deshexapeptide insulin 13.2+ 3.3%. Metabolic clearance rates were reduced compared to insulin (insulin = 19.1 +_ 0.9; despentapeptide insulin = 9.7 _ 0.8; deshexapeptide insulin=6.4_0.6ml.min-l.kg -1 at plasma concentration 0.5 nmol/1). Hypoglycaemic potencies were reduced for both analogues (40% and 30%) when calculated on the basis of plasma concentration although both analogues and insulin were equally effective at lowering plasma glucose concentration in equimolar doses. Plasma half-disappearance time was prolonged (despentapeptide insulin = 7.3 + 0.5; deshexapeptide insulin = 9.1 + 0.2 min). Both analogues were full agonists and conformed to the general relationship between in vitro and in vivo properties seen with a wide range of modified insulins. They resemble other analogues with modifications which reduce receptor affinity without impairing dimerisation or negative cooperativity. The results do not support a physiological role for dimerisation or negative cooperativity.

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“…Japon. June 1984 shows only one half of ability of A-14 insulin (Gliemann et al, 1979;Linde et al, 1981), and that this decreased receptorbinding ability of A-19 insulin is not due to an increased dissociation rate but due to a decreased association rate in the study using cultured human lymphocytes (Watanabe et al, 1984). Since there has been no detailed report on their degradation in adipocytes in which receptor-mediated degradation is the major process for insulin degradation, we investigated these aspects of the labelled insulins using isolated rat adipocytes.…”

Section: Endocrinolmentioning

confidence: 99%

Receptor-mediated degradation by rat adipocytes: Comparison of A-14 with A-19 125I-labelled insulin.

et al. 1984

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Tyrosine A14[125I]monoiodoinsulin: Preparation, Biologic Properties, and long-term stability

Cited by 45 publications

References 0 publications

Scintigraphic distribution of 123 I labelled proinsulin, split conversion intermediates and insulin in rats

Scintigraphic distribution of 123 I labelled proinsulin, split conversion intermediates and insulin in rats

An examination of the role of insulin dimerisation and negative cooperativity using the biological properties of the despentapeptide and deshexapeptide insulins

Receptor-mediated degradation by rat adipocytes: Comparison of A-14 with A-19 125I-labelled insulin.

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