Tremorgenic mycotoxin from Penicillium paraherquei

A tremorgenic mycotoxin was isolated from Penicillium paraherquei Abe ex G. Smith and identified as verruculogen. It was produced at the rate of approximately 1 mg/g of the dried fungal mycelium cultured on peptone-enriched Czapek-Dox medium at 28 degrees C.

Plasmid-mediated penicillin beta-lactamases in Pseudomonas aeruginosa

A penicillin beta-lactamase (PCase) was extracted from Pseudomonas aeruginosa Rms139(+) and purified by means of column chromatography. The isoelectric point of Rms139 PCase was 5.7 and its molecular weight was 22,500 +/- 1,000. The optimal pH for the hydrolysis of benzylpenicillin was 7.0 to 7.5 and the optimal temperature was 45 C, with the PCase also showing high activity against carbenicillin. It is concluded that this enzyme is a new type of penicillin beta-lactamase different from the type I, II, or III R plasmid-mediated PCases reported previously.

Relation between redox potentials and rate constants in reactions coupled with the system oxygen-superoxide

Univalent oxidation-reduction reactions coupled with the oxygen-superoxide system were investigated in the reactions shown in eq 3 and 8, where Q and Q.- stand for p-benzoquinone and p-benzosemiquinone, respectively. From kinetic experiments the following rate constants were obtained at pH 7.0:k3 = 4.5 x 10(4) M-1 sec-1 and k8 = 3 x 10(-2) M-1 sec-1. With known values of k-3 and k-8, and of E0' for the systems Q-Q.- (0.10 V) and Cyt c3+ - Cyt c2+ (0.255 V), the calculated values of E0(O2-O2.-) were found to lie in the range between -0.27 and -0.33 V.