Human C4a des Arg Anaphylatoxin

Abnormalities in the complement system have been described in patients with schizophrenia, with those individuals having greater frequency of complement component 4A (C4A) alleles and higher C4A transcript levels in postmortem brain tissue. Importantly, abnormalities in C4A and other complement molecules have been associated with synaptic pruning abnormalities that occur during neurodevelopment. A few studies have investigated C4 levels in living patients with schizophrenia, but all of them did so using peripheral blood samples. No studies have examined C4 levels in cerebrospinal fluid (CSF), presumably a better biofluid choice given its intimate contact with the brain. Therefore, we report for the first time on C4 levels in CSF and plasma of patients with schizophrenia. In this study, we obtained CSF in 32 patients with schizophrenia spectrum disorders and 32 healthy volunteers and peripheral blood samples in 33 SSD and 31 healthy volunteers. C4 levels were measured using Abcam ELISA assays. Univariate analysis did not show a statistically significant difference in CSF C4 values between groups. However, a multivariable analysis showed a statistically significant increase in CSF C4 levels between groups after adjusting for sex and age. We also observed a high correlation between CSF C4 levels and age. By contrast, plasma C4 levels were not significantly different between groups. CSF and plasma C4 levels were not significantly correlated. Therefore, the use of CSF samples is critical and should be complementary to the use of peripheral blood samples to allow for a comprehensive understanding of complement C4 abnormalities in schizophrenia.

Background: Thermophilic xylanases are valuable in many industrial applications. Results: The structures of a xylanase XynCDBFV and its complex with xylooligosaccharides were determined, and its N-terminal region (NTR) contributes to thermostability. Conclusion: NTR may stabilize the overall protein folding of XynCDBFV. Significance: The structural and functional investigation of unprecedented NTR of XynCDBFV provides a new insight into the molecular basis of thermophilic xylanases. The catalytic domain of XynCDBFV, a glycoside hydrolase family 11 (GH11) xylanase from ruminal fungus Neocallimastix patriciarum previously engineered to exhibit higher specific activity and broader pH adaptability, holds great potential in commercial applications. Here, the crystal structures of XynCDBFV and its complex with substrate were determined to 1.27-1.43 resolution. These structures revealed a typical GH11 -jelly-roll fold and detailed interaction networks between the enzyme and ligands. Notably, an extended N-terminal region (NTR) consisting of 11 amino acids was identified in the XynCDBFV structure, which is found unique among GH11 xylanases. The NTR is attached to the catalytic core by hydrogen bonds and stacking forces along with a disulfide bond between Cys-4 and Cys-172. Interestingly, the NTR deletion mutant retained 61.5% and 19.5% enzymatic activity at 55 degrees C and 75 degrees C, respectively, compared with the wild-type enzyme, whereas the C4A/C172A mutant showed 86.8% and 23.3% activity. These results suggest that NTR plays a role in XynCDBFV thermostability, and the Cys-4/Cys-172 disulfide bond is critical to the NTR-mediated interactions. Furthermore, we also demonstrated that Pichia pastoris produces XynCDBFV with higher catalytic activity at higher temperature than Escherichia coli, in which incorrect NTR folding and inefficient disulfide bond formation might have occurred. In conclusion, these structural and functional analyses of the industrially favored XynCDBFV provide a molecular basis of NTR contribution to its thermostability.