p-Coumaric acid - a monomer in the sporopollenin skeleton

Sporopollenin obtained from wings of Pinus mugo (Turra) pollen was analysed by pyrolysis mass spectrometry. In the spectrum, mass peaks which are characteristic for p-coumaric acid were dominant. p-Coumaric acid was the main degradation compound when the wing material was treated by a gentle method using AII3, and also when the remaining residue of the treated sporopollenin material was saponified. It is therefore assumed that p-coumaric acid is a genuine structural unit in the sporopollenin skeleton. In addition, the effects of AII3 treatment indicate that the p-coumaric acid might be bound by ether linkages.

A stable liquid control material for urinary enzyme assays

A stable liquid control material for urinary enzyme assays was prepared by addition of ethylene glycol (30% v/v) or glycerol (30% v/v) to centrifuged urine, and pH adjustment to 7.0. Tested for 375 days, the material exhibited stable beta-N-acetylglucosaminidase, alanine aminopeptidase, gamma-glutamyltransferase and lactate dehydrogenase activities, at both 4 and -20 degrees C. The material further has been successfully evaluated in an external quality control program.

The effect of new alpha-glucosidase inhibitors (BAY m 1099 and BAY o 1248) on meal-stimulated increases in glucose and insulin levels in man

To confirm findings obtained from animal experiments demonstrating the metabolic effect of two new glucosidase inhibitors, 7 single blind cross-over studies with 42 healthy male volunteers were performed. In each group 6 subjects received 25, 50, 100 and 200 mg BAY m 1099 and 10, 20, and 40 mg BAY o 1248 or placebo with a standardized breakfast. Blood glucose and serum insulin were measured in venous blood before and 30, 60, 90, 120 and 180 min after each of 3 meals. ECG, blood pressure, body weight, monitor ECG and haematological and clinico-chemical parameters were also examined. The postprandial increase in blood glucose and serum insulin after breakfast were significantly and dose-dependently reduced by BAY m 1099. 10 and 20 mg BAY o 1248 not only reduced the increases in blood glucose and serum insulin after breakfast, but also after lunch (10 mg). 40 mg BAY o 1248 prevented the postprandial increase in both metabolic parameters after breakfast (p less than 0.05), an effect which was sustained after lunch. Intestinal problems occurred (flatulence, meteorism, diarrhoea) in 25 of 42 volunteers. Objective tolerability was good. The results of these first clinical pharmacological studies with two new glucosidase inhibitors justify studies on patients with diabetes mellitus.

Specificity of DNA basic polypeptide interactions. II+ Influence of aromatic amino acid residues investigated with agarose bound lysine copolypeptides

Binding affinities towards DNA and base pair specificities of lysine copolymers, containing different amounts of Phe, Tyr or Trp residues, were estimated using a previously described chromatographic method. Incorporation of few aromatic residues into polylysine causes a decrease in the binding affinity, however, further raising the aromatic residue - lysine ratio results in a continous increase of affinity, which is most pronounced with the Tyr copolymers and not observed with polymers containing neutral aliphatic amino acid residues. AT-specificity increases concomitant with binding affinity in the case of the Tyr copolymers but not with the Phe copolymers. The interaction of DNA with the alternating Phe-Lys polymer is significantly stronger than with the random copolymer of equal residue composition. The molecular and conformational reasons determining specificity are discussed.

Cooperative binding of fluorescein-labeled clupeine by DNA

The alpha-amino group of clupeine fraction Z from herring sperm was coupled with fluorescein. Binding of the labeled protamine by DNA is accompanied by significant fluorescence quenching up to 80%. This allowed the convenient determination of the binding behavior of protamine and DNA. Binding was found to be strongly cooperative and not be significantly affected by the size of DNA. The ionic strength dependence in the range up to 0.3 M NaCl was rather small. Binding parameters were derived according to classical unique-site treatment and to a concept which includes vagrant multi-site binding.

Specifity of DNA-basic polypeptide interactions. Influence of neutral residues incorporated into polylysine and polyarginine

An approach is described for evaluation of the specificity of basic polypeptides concerning the base pair composition of DNA. The polypeptides were covalently bound to CNBr activated agarose and two DNAs strongly different in base composition but of equal molecular weight were loaded and detached by a NaCl gradient. The difference in the NaCl concerntrations between the elution maxima of the two DNAs was taken as a measure for the recognition specificity. The results obtained confirmed the known AT- und GC-specificity of polylysine and polyarginine, respectively. Neutral residues incorporated into polylysine generally reduce the interaction affinity and also the AT-specificity of their host. This behavior is very pronounced with three homogeneous fractions of clupeine containing about one third of neutral aliphatic amino acids within clusters of arginine; the base pair specificity of these arginine copolymers was found to be practically nil.