Carbohydrases

The qua si-crystalline stmcture of natural starch granules causes them to be insoluble in water at normal room temperature and gives them relative resistance to carbohydrases other than a-amylase and glucoamylase unless the granules become swollen. Three-dimensional arrangements of crystalline and amorphous zones in starch granules have been suggested (2). 

Portions (50 mU MCA-hydrolsing activity) of purified CinnAE were incubated at 37°C with SBP (10 mg), both in the presence and absence of other carbohydrases, in 100 mM MOPS (pH 6.0) in a final volume of 1 mL. Incubations containing boiled enzyme were performed as controls. Reactions were terminated by boiling (3 min) and the amount of free ferulic acid determined using a method described previously for de-starched wheat bran [18]. The total amount of alkali-extractable ferulic acid present in the SBP was 0.87% [5]. 

SBP was incubated in the presence of carbohydrases either individually, or in pairs, and in the absence or presence of esterase, and the soluble incubation products assayed for feruloyl groups by HPLC. None of the carbohydrases used contained FAE activity. 

S. Kitahata, C. F. Brewer, D. S. Genghof, T. Sawai, and E. J. Hehre, Scope and mechanism of carbohydrase action. Stereocomplementary hydrolytic and glu-cosyl-transferring actions of glucoamylase and glucodextranase with alpha- and beta-D-glucosyl fluoride, J. Biol. Chem., 256 (1981) 6017-6026. 

In nature, amylases act hand in hand with each other and with other carbohydrases in bringing about the rapid breakdown of starches and glycogens to sugars which can be utilized readily by the living cell. Much important and practical information has been accumulated by the use of extracts and crude precipitates in which more or less natural mixtures of enzymes have been studied in the laboratory. However, the... 

It is important to note that no evidence of maltase activity was found in the amylase preparations even when the highest concentrations used in these comparisons were allowed to react for twenty-four hours with one per cent maltose under the conditions for the hydrolysis of starch. Similarly, no evidence was obtained for the presence of any other contaminating or extraneous carbohydrases in the amylase preparations. Partial inactivation of the amylase under a number of different conditions failed to give any evidence of selective inactivation such as might be expected if more than one enzyme were present. The substrates used for measuring the activity of the partially inactivated amylase were starch and starch hydrolyzates that had already been extensively (58) J. Blom, Agnete Bak and B. Braae, Z. physiol. Chem., 250, 104 (1937). 

A recent study, however, has shown that aminopeptidase activity is present on the surface of porcine buccal mucosa, and that various aminopeptidase inhibitors, including amastatin and sodium deoxycholate, reduce the mucosal surface degradation of the aminopeptidase substrate, leucine-enkephalin [149], Since the peptidases are present on the surface of the buccal mucosa, they may act as a significant barrier to the permeability of compounds which are substrates for the enzyme. In addition to proteolytic enzymes, there exist some esterases, oxidases, and reductases originating from buccal epithelial cells, as well as phosphatases and carbohydrases present in saliva [154], all of which may potentially be involved in the metabolism of topically applied compounds. 

Trans-D-glucosylation in the monosaccharide series has been known for a long time,95 but, in the oligosaccharide series, it was first described by Pigman and Blair.96,97 The ability of carbohydrases to catalyze both the hydrolysis and the synthesis of oligosaccharides is now well established. 

Solanum indicum L. Niu Zi Qie (Indian nightshade) (root, leaf, fruit) Diosgenin, solanidine, solanine, solasodine, alkaloids, carbohydrases, maltase, saccharase, melibiase.50 Antidote for poison, for urinary disease. 

Digestion of dietary glycogen and starch in the human body begins with the salivary and pancreatic amylases, which cleave a-1,4 linkages at random. It continues with a glucoamylase found in the brush border membranes of the small intestine where it occurs as a complex with maltase.74 Carbohydrases are discussed in Chapter 12, Section B. 

The use of carbohydrases for the elucidation of the structure of naturally occurring polysaccharides has been reviewed.257 The present discussion will be limited to their use in analyzing the structures of synthetic polysaccharides. 

The difficulties attendant on the isolation of pure enzymes of known specificity is a major barrier to their routine use for the structural analysis of polysaccharides. As the specificities are separated and as the action patterns of carbohydrases become better defined, these enzymes may be expected to play an important and vital role in the investigation of the structure of synthetic polysaccharides containing ordered sequences of sugar residues. Conversely, it may be anticipated that synthetic carbohydrate polymers of known structure will aid in studies of the specificity requirements of purified enzymes. 

Many so-called glycoside hydrolases catalyze some glycosyl transfer to acceptors other than water. However, it has always been assumed that carbohydrases which have strictly or predominantly hydrolytic action on one substrate would necessarily prove solely or predominantly hydrolytic with all utilizable (suitably diluted) substrates. This is the essential assumption of the hydrolase concept it is not made by the glycosylation model, and it is this assumption which our experimental findings, as well as theoretical base, deny. 

As research has progressed in this area, many systems have been shown to follow a similar behaviour. Such phenomena are important in the production of enzymes and metabolites. In industrial applications, these very important control mechanisms usually have to be bypassed for the reliable generation of high concentrations of enzymes. Good examples may be seen in carbohydrase production systems,... 

In 1939, because of his ability, he was awarded a Lalor Fellowship this enabled him to proceed to the University of Leipzig, where he worked under the estimable Professor Burckhardt Helferich, whose exploration of carbohydrases ranks him among the authorities in the field. Just shortly before Ward Pigman passed away, he went to Bonn at the invitation of the German Chemical Society to partake in the celebration of the 90th birthday of his illustrious tutor. 

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