Desoctapeptideinsulin fragments formed by chymotryptic cleavage and suitable for modification of insulin in positions A 14 and B 16

The molecule of desoctapeptide insulin is cleaved by ŕ-chymotrypsin at the three tyrosine residues. The fragments with tyrosine C-terminal residues are candidates of semisynthetic modification. They were isolated and characterized by HPLC, capillary electrophoresis and mass spectrometry

Desoctapeptideinsulin: Substrate of ŕ-chymotrypsin

Desoctapeptideinsulin (DOI) contains three tyrosine residues and therefore it represents a suitable substrate for ŕ-chymotrypsin. The detailed enzymic study reveated a series of intermediates and final products. The bonds formed by tyrosine A14 and B16 are attacked as the first, and the products are further desintagrated

Anaerobic oxidation of methane in grassland soils used for cattle husbandry.

While the importance of anaerobic methane oxidation has been reported for marine ecosystems, the role of this process in soils is still questionable. Grasslands used as pastures for cattle-overwintering show an increase in anaerobic soil micro-sites caused by animal treading and excrement deposition. Therefore anaerobic potential methane oxidation activity of severely impacted soil from a cattle winter pasture was investigated in an incubation experiment under anaerobic conditions using 13C-labeled methane. We were able to detect a high microbial activity utilizing CH4 as nutrient source shown by the respiration of 13CO2. Measurements of possible terminal electron acceptors for anaerobic oxidation of methane were carried out. Soil sulfate concentrations were too low to explain the oxidation of the amount of methane added, but enough nitrate and iron(III) were detected. However, only nitrate was consumed during the experiment. 13C-PLFA analyses clearly showed the utilization of CH4 as nutrient source mainly by organisms harbouring 16:1ω7 PLFAs. These lipids were found in Gram-negative microorganisms and anaerobes. The fact that these lipids are also typical for type I methanotrophs, known as aerobic methane oxidizers, might indicate a link between aerobic and anaerobic methane oxidation