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Insulin: Biosynthesis, Chemistry, and Preparation

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Related Experiment Video

Updated: Jun 10, 2026

Human Pseudoislet System for Synchronous Assessment of Fluorescent Biosensor Dynamics and Hormone Secretory Profiles

Human Pseudoislet System for Synchronous Assessment of Fluorescent Biosensor Dynamics and Hormone Secretory Profiles

Published on: November 3, 2023

Backbone cyclic insulin.

Asser S Andersen¹, Eva Palmqvist, Susanne Bang

¹Protein Expression, Novo Nordisk A/S, Novo Nordisk Park, DK-2760 Maaloev, Denmark.

Journal of Peptide Science : an Official Publication of the European Peptide Society

|July 20, 2010

Summary

Backbone cyclic insulin, created using reverse proteolysis, is as effective as human insulin (HI) in rats. This novel cyclic insulin shows resistance to certain enzymes but has lower receptor affinity.

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Published on: May 10, 2018

Area of Science:

Biochemistry
Protein Engineering
Pharmacology

Background:

Native insulin structure and function are critical for glucose regulation.
Developing insulin analogs with enhanced stability and controlled release is an ongoing challenge.
Enzymatic methods offer precise control in protein modification and cyclization.

Purpose of the Study:

To design and synthesize a backbone cyclic insulin analog.
To evaluate the stability and biological activity of the cyclic insulin.
To explore a novel enzymatic cyclization strategy for protein engineering.

Main Methods:

Single-chain insulin precursor expressed in yeast.
Reverse proteolysis using Achromobacter lyticus protease in partial organic solvent.
LC-MS peptide mapping for structural confirmation.
Enzymatic degradation assays (CPY, chymotrypsin).
In vivo efficacy study in Wistar rats via intravenous administration.

Main Results:

Successfully synthesized backbone cyclic insulin via enzymatic cyclization.
Confirmed the presence of the ring-closing bond and native disulfide bonds.
Demonstrated inertness to CPY but lability to chymotrypsin.
Achieved equipotency to human insulin (HI) in vivo despite lower receptor affinity.

Conclusions:

Enzymatic cyclization is a viable method for creating insulin analogs.
Backbone cyclic insulin exhibits unique stability characteristics.
This approach offers potential for developing novel insulin therapeutics with modified pharmacokinetic profiles.