Naturally Occurring Inhibitors: Carbohydrase Inhibitors

The list of natural inhibitors of carbohydrases in Table 1 includes only those that have been proven to be proteinaceous ² , ³ , ¹¹ , ²¹ , ²⁴ or are believed to be so on the basis of such properties as thermolability and molecular weight. An inhibitor that had been assumed to be a protein, the amylase inhibitor from sorghum, ⁶ has been shown to be a series of oligomeric condensed tannins of the leucocyanide group. ²⁷ Similarly, the pectinase inhibitor from Sericea ²⁸ has been shown to be a polymer of proanthocyanidin. ²⁹ Both of the sorghum and Sericea inhibitors appear to be general protein denaturants. Most of the inhibitors listed, however, are highly specific with respect to the carbohydrase and its source(s). Some are reactive with endogenous enzymes, notably the invertase inhibitors, and may thus have a regulatory function. Others are reactive with enzymes from unrelated sources but not with the endogenous enzymes; these proteins may function as protective agents against microbial and insect damage. The possibility also exists that the ability of certain proteins to inhibit enzymes is fortuitous.