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Carbamate kinase from Streptococcus faecalis is inactivated by butanedione in borate buffer, which implies the presence of an essential arginine at the active site of the enzyme. The inactivation reaction is first order in [butanedione] and a replot of the inactivation rate data infers that one arginine is modified. The enzyme is protected against inactivation by ADP, ATP, the metal-nucleotides and carbamyl phosphate but not by carbamate. Amino acid analyses reveal that one of three arginines is modified by butanedione in the absence of protecting agents, and the binding of ADP to the enzyme prevents modification. Thus, analysis of the data suggest that (i) substrate binding to arginine and (ii) protein conformational changes at the active site are responsible for protection of an essential arginine against modification by butanedione. 相似文献
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Nadler JJ Moy SS Dold G Trang D Simmons N Perez A Young NB Barbaro RP Piven J Magnuson TR Crawley JN 《Genes, Brain & Behavior》2004,3(5):303-314
Mouse models of social dysfunction, designed to investigate the complex genetics of social behaviors, require an objective methodology for scoring social interactions relevant to human disease symptoms. Here we describe an automated, three chambered apparatus designed to monitor social interaction in the mouse. Time spent in each chamber and the number of entries are scored automatically by a system detecting photocell beam breaks. When tested with the automated equipment, juvenile male C57BL/6J mice spent more time in a chamber containing a stranger mouse than in an empty chamber (sociability), similar to results obtained by the observer scored method. In addition, automated scoring detected a preference to spend more time with an unfamiliar stranger than a more familiar conspecific (preference for social novelty), similar to results obtained by the observer scored method. Sniffing directed at the wire cage containing the stranger mouse correlated significantly with time spent in that chamber, indicating that duration in a chamber represents true social approach behavior. Number of entries between chambers did not correlate with duration of time spent in the chambers; entries instead proved a useful control measure of general activity. The most significant social approach behavior took place in the first five minutes of both the sociability and preference for social novelty tests. Application of these methods to C57BL/6J, DBA/2J and FVB/NJ adult males revealed that all three strains displayed tendencies for sociability and preference for social novelty. To evaluate the importance of the strain of the stranger mouse on sociability and preference for social novelty, C57BL/6J subject mice were tested either with A/J strangers or with C57BL/6J strangers. Sociability and preference for social novelty were similar with both stranger strains. The automated equipment provides an accurate and objective approach to measuring social tendencies in mice. Its use may allow higher-throughput scoring of mouse social behaviors in mouse models of social dysfunction. 相似文献
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Since commercial copy number standards are not always available for real-time PCR, alternative sources of DNA are used. Unfortunately, stored genomic DNA or PCR amplicon has been shown to be unstable, resulting in variable copy number. More recently, the use of ultramer as copy number standard has been reported. However, there is little information on the stability of ultramer under different storage conditions. Thus the aim of this study was to determine the stability of ultramer as copy number standard under different storage conditions using different mixing methods. We found that ultramer copy number was not affected by storage at either 4 °C or − 20 °C over a period of 30 days. Furthermore, the method of mixing the ultramer did not appear to contribute to variability in results. Irrespective of storage temperature or mixing method, there was less than 5% variance in Ct value over a period of 30 days. A duplicate set of standards costs approximately $0.01. Therefore, the use of ultramer as copy number standards in real-time PCR, is cost effective and convenient. 相似文献
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Hamajima N Naito M Okada R Kawai S Yin G Morita E Higashibata T Tamura T Nakagawa H Matsuo H Mori A Wakai K 《Gene》2012,503(1):131-136
A genome-wide association study identified that LRP2 rs2544390 in intron 1 was associated with serum uric acid (SUA) levels among Japanese, as well as polymorphisms of SLC22A12, ABCG2, and SLC2A9. This study aimed to confirm the association of rs2544390 C/T with SUA, as well as another LRP2 polymorphism (rs3755166 G/A) in the promoter. Subjects were 5016 health checkup examinees (3409 males and 1607 females) aged 35 to 69years with creatinine<2.0mg/dL. The subjects with SLC22A12 258WW, SLC2A9 rs11722228C allele, ABCG2 126QQ and 141Q allele (2546 males and 1199 females) were selected for analysis. Mean SUA was 6.03mg/dL for CC, 6.18mg/dL for CT, and 6.19mg/dL for TT among males (p=0.012), and 4.49mg/dL, 4.45mg/dL, and 4.42mg/dL among females (not significant), respectively. No association was observed for rs3755166. The association with rs2544390 was stronger among male drinkers. The odds ratio of drinking ≥5/week relative to no drinking for hyperuricemia (SUA≥7mg/dL and/or under medication for hyperuricemia) was 1.11 (95% confidence interval, 0.67-1.84) among CC males, 1.75 (1.22-2.51) among CT males, and 3.13 (1.80-5.43) among TT males. The interaction terms with drinking ≥5/week were 1.56 (p=0.156) for CT and 2.87 (p=0.005) for TT. This was the first report on the interaction between LRP2 genotype and alcohol drinking for SUA. Since the low density lipoprotein-related protein 2 (megalin) encoded by LRP2 is a multi-ligand endocytic receptor expressed in many tissues including the kidney proximal tubules, the association/interaction remained to be confirmed both epidemiologically and biologically. 相似文献