Synthesis of deamino-A<sup>1</sup> sheep insulin

Katsoyannis, Panayotis G.; Zalut, Clyde

doi:10.1021/bi00757a002

Cited by 13 publications

(9 citation statements)

References 25 publications

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“…That is, whereas acetylation of GlyA1 in bisacetyl-insulin (to achieve trisacetyl-insulin, peptide 6) causes a small decrement in receptor-binding potency, acetylation of Ile^in des-GlyA1-bisacetyl insulin (to achieve peptide 7) actually causes a 34-fold increase in the potency of the truncated analogue. Both of these findings have been reported before (Zahn et al, 1972;Katsoyannis & Zalut, 1972). The acetylation of the desdipeptide and destripeptide insulins (peptides 4 and 5) to give peptides amino terminus of the insulin A chain.…”

Section: Resultssupporting

confidence: 73%

Importance of aliphatic side-chain structure at positions 2 and 3 of the insulin A chain in insulin-receptor interactions

Nakagawa¹,

Tager²

1992

Biochemistry

124

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In order to evaluate the cause of the greatly decreased receptor-binding potency of the naturally occurring mutant human insulin Insulin Wakayama ([LeuA3]insulin, 0.2% relative potency), we examined (by the semisynthesis of insulin analogues based on N alpha-PheB1,N epsilon-LysB29-bisacetyl-insulin) the importance of aliphatic side chain structure at positions A2 and A3 (Ile and Val, respectively) in directing the interaction of insulin with its receptor. Analogues bearing glycine, alanine, alpha-amino-n-butyric acid, norvaline, norleucine, valine, isoleucine, allo-isoleucine, threonine, tert-leucine, or leucine at positions A2 or A3 were assayed for their potencies in competing for the binding of 125I-labeled insulin to isolated canine hepatocytes, as were analogues bearing deletions from the A-chain amino terminus or the B-chain carboxyl terminus. Selected analogues were also analyzed by far-UV CD and absorption spectroscopy of Co2+ complexes. Our results identify that (a) Ile and Val serve well at position A2, whereas residues with other side chains (including those with straight chains, alternatively configured beta-branches, or a gamma-branch) exhibit relative receptor-binding potencies in the range 1-5%; (b) greater flexibility is allowed side-chain structure at position A3, with Ile, allo-Ile, alpha-amino-n-butyric acid, and tert-Leu exhibiting relative receptor-binding potencies in the range 11-36%; and (c) simultaneous replacements at positions A2 and A3, and deletions of the COOH-terminal domain of the insulin B chain in related analogues, yield cumulative effects. These findings are discussed with respect to a model for insulin-receptor interactions that involves a structure-orienting role for residue A2, the direct interaction of residue A3 with receptor, and multiple separately defined elements of structure and of conformational adjustment.

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Section: Resultssupporting

confidence: 73%

Importance of aliphatic side-chain structure at positions 2 and 3 of the insulin A chain in insulin-receptor interactions

Nakagawa¹,

Tager²

1992

Biochemistry

124

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“…Yet in insulin, Gly A1 adjoins a free ␣-amino group, whereas in IGF-I, Gly 42 is part of single polypeptide chain. Furthermore, the N-terminal modification of the insulin A-chain or its N-terminal extension impairs IR binding (48,49,57,58). These salient differences suggested IR and IGFR differ near otherwise homologous A1 sites.…”

Section: Discussionmentioning

confidence: 99%

Design of an Insulin Analog with Enhanced Receptor Binding Selectivity

Zhao

Wan

Whittaker

et al. 2009

Journal of Biological Chemistry

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Insulin binds with high affinity to the insulin receptor (IR) and with low affinity to the type 1 insulin-like growth factor (IGF) receptor (IGFR). Such cross-binding, which reflects homologies within the insulin-IGF signaling system, is of clinical interest in relation to the association between hyperinsulinemia and colorectal cancer. Here, we employ nonstandard mutagenesis to design an insulin analog with enhanced affinity for the IR but reduced affinity for the IGFR. Unnatural amino acids were introduced by chemical synthesis at the N-and C-capping positions of a recognition ␣-helix (residues A1 and A8). These sites adjoin the hormone-receptor interface as indicated by photocross-linking studies. Specificity is enhanced more than 3-fold on the following: Epidemiological studies have demonstrated an association between the metabolic syndrome and type 2 diabetes mellitus (DM) 4 with enhanced risk of colorectal cancer (CRC) (1-3). Animal models suggest that this risk is due to hyperinsulinemia (4, 5). An increased risk of CRC is conferred by treated-derived hyperinsulinemia, either as a direct consequence of insulin replacement therapy or as an indirect response to sulfonylurea secretagogues (6 -9). A reduced CRC risk is by contrast associated with metformin treatment, which results in lower circulating insulin concentrations (7). Because of the global epidemic of type 2 DM (10, 11), it would be of interest to develop a form of insulin therapy that does not elevate CRC risk in this clinical setting.A variety of evidence suggests that the association between hyperinsulinemia and CRC is due to aberrant activation of the type 1 IGF receptor (IGFR) (for review see Refs. 5,12). Although underlying molecular mechanisms are incompletely understood, two models have been proposed (5, 12). The first posits cross-binding of insulin to IGFR in colonic epithelia and neoplastic clones, driving proliferation and tumorigenesis; the second proposes indirect IGFR activation through perturbation of the IGF-I axis (including expression of the IGF-binding proteins) (13,14). Whereas consistent changes in bioactive IGF-I have been difficult to document (4), evidence favoring the direct model is provided by studies of epithelial proliferation in rats (15). Exogenous administration of insulin with a euglycemic clamp causes an acute dose-dependent increase in the proliferation rate of colonic epithelia despite decreased IGF-I expression. Such increased proliferation was not observed as a consequence of hyperglycemia or following infusion of a triglyceride emulsion (15).Insulin binds with high affinity (K d ϳ0.05 nM) to the insulin receptor (IR) and with low but significant affinity (K d Ј ϳ9.0 nM) to IGFR (16). Such cross-binding reflects the structural homology between insulin and IGF-I (17) and between IR and IGFR (18). The structural basis for receptor discrimination by insulin and IGF-I has been described recently (19). As a first step toward dissecting the molecular mechanism of insulin-dependent proliferation of colonic epithelia c...

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“…Replacement of GlyA1 of sheep insulin with sarcosine produced nearly equal (83% of native) potency, 101 whereas b-alanine reduced potency by *50%. 39 Des-amino GlyA1 insulin had activity of only 35% relative to native sheep insulin in the mouse convulsion assay, 102 whereas desGlyA1 insulin exhibited 10-25% activity in vivo. 103 Introduction of a chiral center in the form of either L-or D-alanine produced a dramatically lower potency for the former but, surprisingly, full functional activity in the case of the lat-…”

Section: A-chain Residuesmentioning

confidence: 99%

Insulin structure and function

2007

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Throughout much of the last century insulin served a central role in the advancement of peptide chemistry, pharmacology, cell signaling and structural biology. These discoveries have provided a steadily improved quantity and quality of life for those afflicted with diabetes. The collective work serves as a foundation for the development of insulin analogs and mimetics capable of providing more tailored therapy. Advancements in patient care have been paced by breakthroughs in core technologies, such as semisynthesis, high performance chromatography, rDNA-biosynthesis and formulation sciences. How the structural and conformational dynamics of this endocrine hormone elicit its biological response remains a vigorous area of study. Numerous insulin analogs have served to coordinate structural biology and biochemical signaling to provide a first level understanding of insulin action. The introduction of broad chemical diversity to the study of insulin has been limited by the inefficiency in total chemical synthesis, and the inherent limitations in rDNA-biosynthesis and semisynthetic approaches. The goals of continued investigation remain the delivery of insulin therapy where glycemic control is more precise and hypoglycemic liability is minimized. Additional objectives for medicinal chemists are the identification of superagonists and insulins more suitable for non-injectable delivery. The historical advancements in the synthesis of insulin analogs by multiple methods is reviewed with the specific structural elements of critical importance being highlighted. The functional refinement of this hormone as directed to improved patient care with insulin analogs of more precise pharmacology is reported.

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Synthesis of deamino-A¹ sheep insulin

Cited by 13 publications

References 25 publications

Importance of aliphatic side-chain structure at positions 2 and 3 of the insulin A chain in insulin-receptor interactions

Importance of aliphatic side-chain structure at positions 2 and 3 of the insulin A chain in insulin-receptor interactions

Design of an Insulin Analog with Enhanced Receptor Binding Selectivity

Insulin structure and function

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Synthesis of deamino-A1 sheep insulin

Cited by 13 publications

References 25 publications

Importance of aliphatic side-chain structure at positions 2 and 3 of the insulin A chain in insulin-receptor interactions

Importance of aliphatic side-chain structure at positions 2 and 3 of the insulin A chain in insulin-receptor interactions

Design of an Insulin Analog with Enhanced Receptor Binding Selectivity

Insulin structure and function

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Synthesis of deamino-A¹ sheep insulin