Here a chitin deacetylase secreted by Rhizopus circinans was purified to homogeneity and partially characterized. The enzyme exhibits an apparent molecular weight of similar to 75 kDa. At 37 degrees C it shows optimal activity at pH 5.5-6. Its pH stability and thermal stability are good. Mn(2+) and Mg(2+) slightly enhance the activity of the enzyme and Cu(2+) strongly
inhibits it. An R. circinans cDNA library was constructed and screened with a homologous probe synthesized by RT-PCR or with synthetic primers derived from the N-terminal amino-acid sequence of the native purified chitin deacetylase. Three chitin deacetylase cDNAs (RC, D2, and I3/2) were isolated from the cDNA library and sequenced. These cDNAs exhibit features characteristic of chitin deacetylase sequences: the presence of a polysaccharide deacetylase domain, a metal-binding triad, the buy Staurosporine conserved catalytic residues, and high homology with various chitin deacetylase genes. The cDNAs were cloned in a Pichia pastoris expression system and produced as polyhistidine-tagged proteins. Only one recombinant enzyme (called RC) was active under the tested conditions. It was purified to homogeneity in a single step and further characterized. The protein showed an apparent molecular mass of similar to
75 kDa and, like the native enzyme, showed optimal activity at pH 5.5-6 at 37 degrees C. It was strongly inhibited by Cu(2+). The isolation of several chitin deacetylase cDNAs from the same microorganism is discussed. (C) 2008 Elsevier Inc. All rights reserved.”
“Recent PU-H71 purchase Birinapant years have witnessed a resurgence of classic tensions concerning the fundamental nature of human knowledge and the processes underlying its acquisition. This tension, especially evident in research on
the acquisition of words and concepts, arises when researchers pit one type of content against another (perceptual versus conceptual) and one type of process against another (associative versus theory-based). But these dichotomies are false; they rest upon insufficient consideration of the structure and diversity of the words and concepts that we naturally acquire. As infants and young children establish categories and acquire words to describe them, they take advantage of both perceptual and conceptual information, and relate this to both the (rudimentary) theories they hold and the statistics that they witness.”
“Critical limb ischemia causes severe damage to the skeletal muscle. This study develops a reproducible model of myotube ischemia by simulating, in vitro, the critical parameters that occur in skeletal muscle ischemia. Monolayers of C2C12 myoblasts were differentiated into mature myotubes and exposed to nutrition depletion, hypoxia and hypercapnia for variable time periods. A range of culture media and gas mixture combinations were used to obtain an optimum ischemic environment.