A 15 Asn,A 17 Pro,A 21 Ala] insulin was synthesized by the Fmoc solid phase synthetic method to study the biological significance of the helix in the C terminal region of A chain of insulin.In order to make this helix unable to form,Asn and Pro were utilized to substitute A 15 Gln and A 17 Glu,respectively,according to the Chuo Fasman method.The biological activity assays showed that this insulin analogue held only 10% of the biological activities of native insulin.The results suggest that the loss of the A12 18 helix in A chain leads to a remarkable decrease of biological activities of insulin,and this helix is significant to the three dimensional structure and biological functions of insulin.
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