Published online Jun 15, 2000. doi: 10.3748/wjg.v6.i3.371
Revised: February 3, 2000
Accepted: February 29, 2000
Published online: June 15, 2000
AIM: To study the relationship between insulin A chain regions and insulin biological activities, we designed a series of insulin analogues with changes at A21, A12-18 of C-terminal helical region and A8-10 located in the region of A6-A11 intra-chain disulphide bond.
METHODS: Insulin A-chain analogues were prepared by stepwise Fmoc solid-phase manual synthesis and then combined with natural B-chain of porcine insulin to yield corresponding insulin analogues. Their biological activities were tested by receptor binding, mouse convulsion and immunological assay.
RESULTS: [A21Ala]Ins retains 70.3% receptor binding capacity and 60% in vivo biological activity. [DesA13-14, A21Ala]Ins and [DesA12-13-14-15, A21Ala] Ins still have definite biological activity, 7.9% and 4.0% receptor binding, and 6.2% and 3.3% in vivo biological activity respectively. [A15Asn, A17Pro, A21Ala]Ins maintains 10.4% receptor binding and 10% in vivo biological activity. [A8His, A9Arg, A10Pro, A21Ala]Ins, [A8His, A9Lys, A10Pro, A21Ala]Ins and [A8His, A9Lys, A10Arg, A21Ala]Ins have 51.9%, 44.3% and 32.1% receptor binding respectively, 50%, 40% and 30% in vivo biological activity respectively, and 28.8%, 29.6% and 15.4% immunological activity respectively.
CONCLUSION: A21Asn can be replaced by simple amino acid residues. The A chains with gradually damaged structur al integrity in A12-18 helical region and the demolition of the A12-18 helical region by the substitution of Pro and Asn for A17Glu and A15Gln respectively ca n combine with the B chain and the combination products show definite biological activity, the helical structure of A12-18 is essential for biological activities of insulin. A8-10 is not much concerned with biological activities, but is much more important antigenically in binding to its antibodies, these results may help us design a new type of insulin analogue molecule.