Reducing values: dinitrosalicylate gives over-oxidation and invalid results whereas copper bicinchoninate gives no over-oxidation and valid results.

A comparative study was made between two carbohydrate reducing value methods, a relatively old, highly alkaline, 3,5-dinitrosalicylic acid (DNSA) method and a relatively newer, low alkaline (pH 10.5), copper bicinchoninate (CuBic) method. Reducing values for a series of equimolar amounts of maltose-maltohexaose, isomaltose-isomaltohexaose, and cellobiose-cellohexaose were compared by the two methods.

Tests for the mechanism of starch biosynthesis: de novo synthesis or an amylogenin primer synthesis.

Studies in 1940 on potato phosphorylase reaction with starch found that d-glucopyranose from α-d-glucopyranosyl-1-phosphate was added to the nonreducing-ends of starch chains. This led to the hypothesis that the biosynthesis of starch required a preformed primer. Later it was found that phosphorylase was exclusively a degradative enzyme in vivo and that starch-synthase was the enzyme that reacted with ADPGlc to biosynthesize starch.

Significant increases in potato Starch-Synthase and Starch-Branching-Enzyme activities by dilution with buffer containing dithiothreitol and polyvinyl alcohol 50 K.

We have recently found that the dilution of purified potato Starch-Synthases (SS) and Starch-Branching-Enzymes (SBEs), by a glycine buffer (pH 8.5), containing 1.0mM dithiothreitol (DTT) and 0.

Potent inhibition of starch-synthase by Tris-type buffers is responsible for the perpetuation of the primer myth for starch biosynthesis.

Mukerjea and Robyt [Carbohydr. Res. 2012, 352, 137-142] showed that a primer-free potato starch-synthase synthesized starch chains de novo, without the addition of a primer.

De novo biosynthesis of starch chains without a primer and the mechanism for its biosynthesis by potato starch-synthase.

The starch-synthase enzymes used in this study were the second acetone precipitate and Fractions 21 and 23, Table 1, [Mukerjea, Ru.; Falconer, D. J.