L. G. Paleg

Bio: L. G. Paleg is an academic researcher. The author has contributed to research in topics: Citric acid. The author has an hindex of 1, co-authored 1 publications receiving 99 citations.

Assay methods for pectic enzymes

Abstract: Publisher Summary The characterization and purification of a pectic enzyme is often complicated by the presence of other pectic enzymes produced by the source microorganism. This chapter describes three assay procedures that address this problem. Pectic enzymes from Erwinia spp. is used as examples in the chapter. The assays are readily adapted to the analysis of pectic enzyme complexes of other organisms and can be used with crude preparations. Results from plant tissue extracts should be interpreted cautiously, however, because of the prevalence of pectic enzyme inhibitors. The activity stains in the first procedure enable rapid approximation of the number and type of pectic enzymes in the sample and can guide purification strategies, particularly when used in conjunction with titration curves. The second and third procedures permit quantitative assay of hydrolytic and β-eliminative pectic enzymes, respectively. The action patterns of purified pectic enzymes are determined by viscometric and reaction product analyses; oligogalacturonides are resolved by paper chromatography or thin-layer chromatography and detected with bromphenol blue or thiobarbituric acid spray reagent.

Cooperativity of Esterases and Xylanases in the Enzymatic Degradation of Acetyl Xylan

Abstract: Xylan exists in many plants in an acetylated form, a circumstance largely neglected in studies of its breakdown by microbial enzymes. The present investigation demonstrates that fungal esterase and xylanase activities act cooperatively in hydrolyzing acetyl xylan. In the absence of esterase, xylanases break only a limited number of glycosidic bonds. Both the extent and rate of breakdown increase when esterase is present. The two activities also act synergistically to liberate acetyl residues. The prominent effect of esterase action on the hydrolysis of glycosidic bonds suggests that its role will require consideration in processes where acetyl xylan is a substrate.

Physiological Effects of Gibberellic Acid. II. On Starch Hydrolyzing Enzymes of Barley Endosperm

Abstract: Two reports have appeared (15, 22) dealing with the effects of gibberellic acid (GA) on intact germinating barley. Both studies were carried out in an attempt to determine whether or not GA influenced the malting behavior of the barley, and extended the earlier observations of Hayashi (6) that GA speeded up germination and the various processes associated with germination, resulting in an enhancement of malt extract yield. GA, in both reports, markedly stimulated a-amylase activity and increased the growth of the leaf. Sandegren and Beling (22) came to the conclusion that the reduction in germination time (or, in other words, the hastening of starch hydrolysis, etc.) was due to GA's effect on embryo growth. The first paper of this series (19) presented evidence of the production of reducing sugars and an increase in amylase activity resulting from the treatment of barley endosperm with GA. Although it has not yet been possible to demonstrate a direct relationship between increased amylase activity and the production of reducing sugars in the intact grain, several results, such as anion and heat effects, and the increased liberation of maltose, lend circumstantial support to the importance of the role of amylase activity in starch hydrolysis in the isolated endosperm. These results also lead to the suggestion that an endogenous gibberellin, such as that present in germinating barley (21), might, in fact, play an important hormonal role during the germination process, and prompted a closer investigation of the changes in starch hydrolyzing activity of solutions obtained from water, and GA-treated barley endosperm. It should be borne in mind that the results discussed here were obtained with barley endosperm alone, i.e., after the embryo had been removed.