Detection of chitinase activity by 2-aminobenzoic acid labeling of chito-oligosaccharides

Chitinases are hydrolases capable of hydrolyzing the abundant natural polysaccharide chitin. Next to artificial fluorescent substrates, more physiological chito-oligomers are commonly used in chitinase assays. Analysis of chito-oligosaccharides products is generally accomplished by UV detection. However, the relatively poor sensitivity poses a serious limitation. Here we report on a novel, much more sensitive assay for the detection of chito-oligosaccharide reaction products released by chitinases, based on fluorescent detection, following chemical labeling by 2-aminobenzoic acid. Comparison with existing UV-based assays, shows that the novel assay offers the same advantages yet allows detection of chito-oligosaccharides in the low picomolar range.     

Symbiosestudien III: Die intrazellluare bakterien- symbiose von mastotermes darwiniensis froggatt (isoptera).

Ohne Zusammenfassung     

INFANTILE DIARRHEA—Tolerance to Solutions of Electrolytes by Mouth

Since Darrow''s recommendation of electrolyte administration by mouth to infants with diarrhea, the constituting of a palatable liquid has been in the minds of all persons concerned with the treatment of diarrhea. Owing to the frequent association of gastric distress with oral administration of electrolyte solution, presumably because of increased osmolarity, a study was made at Kern County General Hospital to determine what osmolarity of solution was tolerated by most infants. For this purpose a commercially prepared oral electrolyte solution was used. When this new solution was given undiluted—that is, at an osmolarity of 20 times that of physiologic solution—only one of 29 patients, who were acutely ill and dehydrated, refused it or vomited it, probably due to irritation of the gastric mucosa. However, at a dilution of 1:3 with 5 per cent glucose and an osmolarity of six times physiological, only one of the 29 infants vomited and two others occasionally refused it.The length of hospital stay was not shortened by the substitution of the commercial preparation in either dilution. However, since the babies readily drank this electrolyte solution, it was possible to stop parenteral administration of electrolytes once fluid replacement had been carried out when the patient was first admitted.     

Musicality in human evolution,archaeology and ethnography

This essay reviews Iain Morley’s The Prehistory of Music, an up-to-date and authoritative overview of recent research on evolution and cognition of musicality from an interdisciplinary viewpoint. Given the diversity of the project explored, integration of evidence from multiple fields is particularly pressing, required for any novel evolutionary account to be persuasive, and for the project’s continued progress. Moreover, Morley convincingly demonstrates that there is much more to understanding musicality than is supposed by some theorists. I outline Morley’s review of the archaeological and ethnographic literature, and then go on to critique his assessment of philosophical and evolutionary theories, offering some alternative perspectives that might better benefit his project.     

Escherichia coli S-adenosylmethionine decarboxylase. Subunit structure, reductive amination, and NH2-terminal sequences

S-Adenosylmethionine decarboxylase is one of a small group of enzymes that use a pyruvoyl residue as a cofactor. Histidine decarboxylase from Lactobacillus 30a, the best studied pyruvoyl-containing enzyme, has an (alpha beta)6 subunit structure with the pyruvoyl moiety linked through an amide bond to the NH2-terminal of the larger alpha subunit (Recsei, P. A., Huynh, Q. K., and Snell, E. E. (1983) Proc. Natl. Acad. Sci. U. S. A. 80, 973-977). To examine potential structural analogies between the two enzymes, we have isolated and partially characterized S-adenosylmethionine decarboxylase. The purified enzyme comprises equimolar amounts of two subunits of Mr = 14,000 and 19,000 (by sodium dodecyl sulfate-polyacrylamide gel electrophoresis) and has a native molecular weight of 136,000 (by gel filtration). Approximately 4 mol of [methyl-3H] adenosylmethionine are incorporated per mol of enzyme (Mr = 136,000) when the enzyme is inactivated with this substrate and NaCNBH3. These data suggest an (alpha beta)4 structure with 1 pyruvoyl residue for each alpha beta pair. The two subunits have been separated by reversed-phase high performance liquid chromatography after reduction and carboxymethylation. The smaller subunit (beta) has a free amino terminus. The amino terminus of the larger subunit (alpha) appears to be blocked by a pyruvoyl group; this subunit can be sequenced only after this group is converted to an alanyl residue by reduction with sodium cyanoborohydride in the presence of ammonium acetate. This work suggests that S-adenosylmethionine decarboxylase is structurally much more similar to histidine decarboxylase than previously thought.