AJP - Gastrointestinal and Liver Physiology, Vol 243, Issue 3 214-G217, Copyright © 1982 by American Physiological Society
Selective modification of the ability of cholecystokinin to cause residual stimulation of pancreatic enzyme secretion
M. L. Villanueva, J. Martinez, M. Bodanszky, S. M. Collins, R. T. Jensen and J. D. Gardner
In the C-terminal heptapeptide of cholecystokinin
(-Tyr(SO3H)-Met-Gly-Trp-Met-Asp-Phe-NH2), replacing the aspartic acid
residue by beta-aspartic acid did not alter the ability of the peptide to
cause stimulation, desensitization, or residual stimulation of enzyme
secretion from dispersed pancreatic acini. Replacing the tyrosine sulfate
residue by hydroxynorleucine sulfate did not alter the ability of the
heptapeptide to cause stimulation or desensitization, but caused a 50-fold
decrease in the potency with which the peptide caused residual stimulation
of enzyme secretion. These findings suggest that a modification of the
N-terminal region of cholecystokinin heptapeptide, which does not alter the
ability of the peptide to bind to its receptor on pancreatic acini and by
so doing cause stimulation and desensitization of enzyme secretion, can
increase the rate at which the bound peptide dissociates when the acini are
washed and reincubated. This increased dissociation is reflected by a
reduction in the potency with which the peptide causes residual stimulation
of enzyme secretion.
