Buffalo M-proinsulin, containing the initiation methionine, was produced in Escherichia coli and purified to give M(r) of 8812. Following the replacement of 99% of the exchangeable hydrogen atoms with deuterons a preparation containing 131 D atoms was obtained. Buffer exchange of the latter into a protio medium led to, the immediate release of 109 (+/- 1) D atoms
into the medium and the retention of 22 (+/- 1) D atoms in the protein. The slow exchange of these D atoms was studied at 0 degrees C/pH 2.8. Insulin derived from buffalo proinsulin as well as bovine when deuteriated and buffer exchanged, similarly, gave the retention of 25 (+/- 1) D atoms. The data show that the secondary structure of the insulin core present within buffalo/bovine proinsulin contains 5 (+/- 1) fewer slow exchanging hydrogen atoms than are present in the final hormone. This effect is attributed, predominantly, to the long range influence of the SN-38 manufacturer C-peptide, composed of 26 residues, on the insulin core of buffalo proinsulin. In contrast, in the case of human proinsulin, comprising 31 amino acids in the C-peptide, the secondary structure of the insulin core within human proinsulin
is closer to that of insulin itself. (C) 2010 GS-7977 price Elsevier B.V. All rights reserved.”
“QuikChange is a popular method for site-directed mutagenesis in structural and functional studies of proteins and nucleic acids. However, the standard protocol is often inefficient in producing the desired mutations. Here we present a novel CHIR-99021 cell line strategy for primer design,
central overlapping primers (COP), which employs a pair of bipartite primers of different lengths, with the short primer complementary to the middle region of the long primer. The COP method is efficient and robust in generating approximately 90% mutation rate without supercompetent Escherichia coli cells or laborious screening for positive clones. (C) 2011 Elsevier Inc. All rights reserved.”
“BACKGROUNDThe atypical cytologic diagnostic category is ambiguous and presents a management problem for pathologists and clinicians. This meta-analysis reviewed the frequency and cancer risk associated with atypical diagnoses in endoscopic ultrasound-guided fine-needle aspiration (EUS-FNA) specimens of solid pancreatic lesions.\n\nMETHODSPubMed and Scopus were searched using the keywords EUS-FNA and pancreas. Articles were screened focusing on studies of solid lesions. Studies with information regarding the frequency and outcomes of atypical diagnoses were included; the suspicious category was excluded from the analysis. The frequency of atypical diagnoses and the associated risk were calculated using the Comprehensive Meta-Analysis software. The authors assessed whether the following factors explained the heterogeneity of the studies: rapid on-site interpretation; type of reference standard; the study type, size, and site; and the frequency of inadequate, atypical, and positive categories.