The Escherichia coli periplasmic peptidyl-prolyl isomerase (PPIase) SurA is involved in the maturation of outer membrane porins. SurA consists of a substantial N-terminal region, two iterative parvulin-like domains and a C-terminal tail. Here we show that a variant of SurA lacking both parvulin-like domains exhibits a PPIase-independent chaperone-like activity in vitro and almost completely complements the in vivo function of intact SurA. SurA interacts preferentially (>50-fold) with in vitro synthesized porins over other similarly sized proteins, leading us to suggest that the chaperone-like function of SurA preferentially facilitates maturation of outer membrane proteins.
A monoclonal antibody to Schistosoma japonicum which conferred significant protection against cercarial challenge in mice was produced. The predicted translation product of the cDNA corresponding to the antigen recognized by this antibody was homologous to a newly identified family of actin-binding proteins. The expressed protein bound polymerized actin and was recognized by serum from patients infected with S. japonicum.
As there are no data about the chemical composition of this species in Yugoslavia, three populations were taken under examination, of which two were collected from the Vardar area (South Macedonia) and one from the Sava area (North Serbia). Plant material was taxonomically determined by H. Janèid, and samples are deposited in the Herbarium of the Department of Botany, Pharmaceutical Faculty, University of Belgrade. Essential oils were obtained by steam distillation and analyzed by the GC-MS, using a fused silica column, packed with 0.25ym BPI, 15m x 2mm, and temperature programed from 40°C up to 240°C (4 °C/min). Identificaton of each individual compound was made by comparison of their retention times with those of authentic samples and by computer searching, matching mass spectral data with those held in the computer library. The obtained results are presented in Table 1. The examined populations showed a great variability in essential oil composition. Unexpected differences were found between populations A and B, collected from the neighbouring areas. Population A can he classified into the carvone-dihydrocarvone chemotypes, reported previously by Kokkini et al. (3), while population B with high content of menthone-isomenthone cannot be fitted into any of the reported chemotypes, as well as population C with high content of menthofuran and considerable amounts of sesquiterpenes (1, 2). The present results suggest a great interspecies variability in the essential oils of Mentha species, in particular, Men thu longzfolia L., growing in Yugoslavia.
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