A Study of the Influence of a Number of Factors upon the Stability and upon the Activity of Pancreatic Amylase¹

Abstract

The stability and the activity of pancreatic amylase are exceedingly sensitive to its chemical environment. This paper reports additional observations concerning some of the factors concerned. The work was carried out with three times crystallized electrophoretically homogeneous amylase. The factors studied include: the influence of the pH of its aqueous solutions upon the stability of the amylase at different temperatures; the influence of the concentration of the amylase upon its stability in aqueous solution; the influence of calcium and of chloride ions upon the stability and upon the activity of the amylase. Previous evidence has shown that pancreatic amylase requires certain anions for its action and that chloride ions are outstanding in this respect. These findings have been confirmed and extended. Chloride ions also protect the amylase from inactivation in aqueous solution. On the other hand, while calcium ions also protect pancreatic amylase from inactivation in aqueous solution, they have no influence upon the activity as distinguished from the stability of the amylase. The evidence makes it clear that there is a fundamental difference between the protection of the amylase from loss of activity, a protection which, under the conditions studied is exerted to very nearly the same extent by chloride and by calcium ions, and the activation of the amylase by chloride and by certain other anions. This difference is being investigated.

Phytate in pig and poultry nutrition

“…Phytic acid should also be structurally capable of binding with starch through phosphate links (Badenhuizen, ) and should directly reduce starch digestion (Thompson et al., ). Moreover, as Ca is required for amylase activity (Caldwell and Kung, ), its complexation by phytate may lead to reduced enzyme activity. In reverse, Ca addition may react with phytic acid, making it less available for amylase binding (Thompson et al., ).…”

The microbiology of phytic acid metabolism by gut bacteria and relevance for bowel cancer

“…Phytic acid also appears capable of inhibiting starch hydrolysis in the small intestine (Plaami, 1997), a consequence of this is that a greater proportion of starch is made available for gut bacterial fermentation with the production of SCFA to lower colonic pH and thus precipitates potential carcinogens such as secondary bile acids and ammonia (Cummings, 1995). Phytic acid is thought to inhibit starch hydrolysis by either binding directly to the starch through phosphate links (Caldwell & King, 1953) or reducing the efficiency of the enzyme salivary amylase by binding Ca 2+ (which is essential for the functioning of the enzyme) or by binding directly to enzyme itself (Thompson et al ., 1987). Lastly, phytic acid can also compete for binding sites of insulin‐like growth factor II (IGF II), these sites are over expressed in gastrointestinal cancer cell lines and are important for increasing cellular proliferation in tumours (Sullivan et al ., 1995; Lamonerie et al ., 1995).…”