Objective To investigate the expression of cystatin C(Cys C)and high-density lipopro-tein cholesterol(HDL-C)in the serum of patients with Alzheimer's disease(AD)and vascular dementia(VD),and their clinical application.Methods A total of 40 AD patients(AD group)and 40 VD patients(VD group)admitted to Jinhua Second Hospital from January 2020 to January 2022 were enrolled,and another 40 healthy individuals who taking physical examination in the hospital during the same period were subjected as control group.According to Montreal Cognitive Assessment Scale(MoCA)score,the AD patients were divided into mild(22 cases)and moderate to severe(18 cases)AD groups,and the VD patients were into mild(MoCA score 18-26,24 cases)and moderate to severe(MoCA score＜17,16 cases)VD group.Serum levels of Cys C and HDL-C were detected in all the participants,and the diagnostic efficacy of serum Cys C and HDL-C level for AD and VD was analyzed with ROC curve analysis.Results The serum levels of TC,TG,LDL-C and Cys C were significantly higher,and that of HDL-C was obviously lower in the AD and VD groups than the control group(P＜0.05).The Cys C level in the moderate to severe AD group and the moderate to severe VD group was higher than that in the mild AD group and the mild VD group(P＜0.05).There was no significant difference in HDL-C level among moder-ate to severe AD group,moderate to severe VD group,mild AD group and mild VD group(P＞0.05).The AUC value for the combined Cvs C and HDL-C for diagnosis of AD and VD were 0.980(95％CI:0.943-1.000)and 0.951(95％CI:0.905-0.996),respectively.Conclusion Detec-ting serum Cys C and HDL-C levels is simple and convenient.There are significant differences in their serum levels in the patients with AD and VD when compared with healthy population,which may become reference indicators for screening AD and VD.

The chalcone synthase (CHS) superfamily of the type III polyketide synthases (PKSs) generates backbones of a variety of plant secondary metabolites. Benzalacetone synthase (BAS) catalyzes a condensation reaction of decarboxylation between the substrates of 4-coumaric coenzyme A and malonyl coenzyme A to generate benzylidene acetone, whose derivatives are series of compounds with various biological activities. A BAS gene Pcpks2 and a bifunctional CHS/BAS PcPKSI were isolated from medicinal plant P. cuspidatum. Crystallographic and structure-based mutagenesis studies indicate that the functional diversity of the CHS-superfamily enzymes is principally derived from small modifications of the active site architecture. In order to obtain an understanding of the biosynthesis of polyketides in P. cuspidatum, which has been poorly described, as well as of its activation mechanism, PcPKS2 was overexpressed in Escherichia coli as a C-terminally poly-His-tagged fusion protein, purified to homogeneity and crystallized, which is helpful for the clarification of the catalytic mechanism of the enzyme and lays the foundation for its genetic engineering manipulation.
Butanones ; Catalytic Domain ; Crystallization ; Fallopia japonica ; enzymology ; Polyketide Synthases ; genetics ; metabolism

Glycosyltransferases (GTs) catalyze the transfer of a sugar residue of an activated sugar donor to an acceptor molecule. Many families 1 GTs utilize an uridine diphosphate (UDP) activated sugar as donor in the glycosylation reaction, and most of these belong to a group of GTs referred to as the UGTs. The relationship between the degree of amino acid sequence identity and substrate specificity of the plant UGTs is highly complicated, and the prediction of substrate specificity based on phylogenetic analyses need to be improved by more biochemical characterization. This review summarizes the three dimensional structures of plant UGTs published in the Protein Data Bank (PDB), including the detailed substrate interactions with the sugar and receptor binding pockets and mutational analyses of some critical amino acids. It will be helpful for biochemical characterization the substrate specificity of the individual UGT, and lay the foundation for the enzymatic and genetic manipulation of plant UGTs in the future.
Amino Acid Sequence ; Glycosylation ; Glycosyltransferases ; chemistry ; Phylogeny ; Plant Proteins ; chemistry ; Plants ; enzymology ; Protein Structure, Tertiary ; Substrate Specificity ; Uridine Diphosphate ; chemistry

Resveratrol is a natural phytoalexin with special pharmacological and health functions. Stilbene synthase (STS) is a key and rate-limiting enzyme in the biosynthesis of resveratrol that is present only in a limited number of plants. The content of resveratrol from Polygonum cuspidatum is more than 1000 times higher than grapes and peanuts. We speculate that the catalytic ability of different STS may be one of the reasons causing differences in the content of resveratrol. To verify the above speculation, Vitis vinifera stilbene synthase gene (VvSTS) was amplified according to overlap PCR protocol with genomic DNA as template. VvSTS and PcSTS (PcPKS5) were analyzed through heterologous expression in Escherichia coli. The expression products were purified with Ni-NTA sepharose affinity chromatography and desalted through PD-10 column. The molecular weight of the two fusion proteins was about 43 kDa. Enzyme reaction and product analysis showed that the two products were resveratrol. The enzyme kinetic analysis showed that the catalyze efficiency (Kcat/Km) of PcPKS5 was 2.4 times of the VvSTS. Our findings confirms that STS from certain plants has much higher catalytic capability.
Acyltransferases ; metabolism ; Fallopia japonica ; enzymology ; Recombinant Fusion Proteins ; biosynthesis ; Stilbenes ; metabolism ; Vitis ; enzymology

Plant type III polyketide synthase (PKS) generates backbones of a variety of plant secondary metabolites with diverse functions, and has long been models to elucidate the relationship between the three-dimensional structure and function. More than 80 type IIII PKS crystal structures with different functions have been reported in Protein Data Bank, including the crystal structures of the well-studied Chalcone Synthase of plant type III PKS, as well as the 6 other kinds of PKSs in the family, which are critical for understanding the structural basis for diverse starter molecule selectivity, polyketide chain length and the cyclization reaction. Structure-based analysis and site-directed mutagenesis are foundation for the investigation of enzyme engineering, genetic and metabolic engineering. This review summarized 7 plant-specific type III PKS in the aspects of their crystal structures and functions.
Acyltransferases ; chemistry ; genetics ; physiology ; Amino Acid Sequence ; Catalysis ; Chalcones ; Crystallization ; Flavanones ; Genetic Engineering ; Metabolic Engineering ; Molecular Sequence Data ; Plant Proteins ; chemistry ; genetics ; physiology ; Plants ; enzymology ; genetics ; Protein Structure, Secondary ; Substrate Specificity

Objective To examine the prevalence of and risk factors for syphilis among men who have sex with men (MSM) in 16 cities/districts, 6 provinces in China. Methods Based on a previous survey on the entertainment place and population size of MSM, a cross-sectional study was conducted in 2007 using non-probability sampling method among MSM in 16 cities/districts in China.Information about the demography,risk behavior and syphilis infection was collected through questionnaires from MSM. Univariate and multivariate stepwise logistic regression model was constructed to evaluate independent factors associated with syphilis. Results A total of 4211 participants were recruited. The mean age of these participants was 28 years. Among them, 66.7% were self identified as homosexual, 72.5% were unmarried, and 76.4% had an education beyond senior middle school; in the past 6 months, 8.7% had sexual contact with more than 10 male sex partners, 5.6% had ever paid for male sex service, 11.3% had provided commercial sex service to males, and 18.9% had sexual contact with females, while condom was consistently used in only 36.3% of male-to-male anal sexual behavior. Syphilis was diagnosed in 10.6% of these participants. The risk factors independently associated with syphilis included being older than 25 years (adjusted OR = 1.7; 95% CI:1.3-2.0), local residency (adjusted OR = 1.3; 95% CI: 1.0-1.7), being recruited from a bar or a park (adjusted OR = 1.3; 95% CI: 1.1-1.7), having ever paid for a male sex service(adjusted OR = 1.5; 95% CI: 1.0-2.1),inconsistent condom use during male-to-male anal sexual behavior(adjusted OR = 1.2; 95% CI: 1.0-1.5 ), self reported sexually transmitted infection history (adjusted OR = 1.3; 95% CI: 1.0-1.7). Conclusions There is a high prevalence of syphilis in MSM in the 16 Chinese cities where male-to-male commercial sex service and unsafe sexual behavior are common. Further efforts are urgently needed to scale-up the prevention of and treatment program for syphilis among MSM, which should include syphilis and HIV screening as well as education on the use of condom.