Assay Development for Metal-Dependent Enzymes-Influence of Reaction Buffers on Activities and Kinetic Characteristics.

Buffers are often thought of as innocuous components of a reaction, with the sole task of maintaining the pH of a system. However, studies had shown that this is not always the case. Common buffers used in biochemical research, such as Tris (hydroxymethyl) aminomethane hydrochloride (Tris-HCl), can chelate metal ions and may thus affect the activity of metalloenzymes, which are enzymes that require metal ions for enhanced catalysis.

Effects of Ultrasonic Surface Rolling on the Localized Corrosion Behavior of 7B50-T7751 Aluminum Alloy.

The effects of an ultrasonic surface rolling process (USRP) on the localized corrosion behavior of 7B50-T7751 aluminum alloy in a sodium chloride + hydrogen peroxide solution were investigated through microstructural observation, immersion testing, and electrochemical measurements. The results revealed that this alloy is prone to pitting. However, the localized corrosion resistance can be significantly improved via both one-pass USRP and 12-pass USRP treatment.

Effect of the Ultrasonic Surface Rolling Process on the Fretting Fatigue Behavior of Ti-6Al-4V Alloy.

The effect of the ultrasonic surface rolling process (USRP) on the rotary bending fretting fatigue (FF) of Ti-6Al-4V alloy was investigated. The reason for the USRP's ability to improve the FF resistance of Ti-6Al-4V alloy was studied. The results revealed that the USRP induced a compressive residual stress field with a depth of 530 μm and a maximum residual stress of -930 MPa.

[Effect of Codonopsis Radix maintained with sulfur fumigation on immune function in mice].

Objective: To investigate the immune function of mice being given the extract of Codonopsis Radix maintained with sulfur fumigation.

Methods: Mice were divided into five groups. Except the normal control group, the mice were fed with the extract of Codonopsis Radix maintained with sulfur fumigation at the high,medium and low doses, as well as medium dose of Codonopsis Radix maintained with low-temperature vacuum method, respectively.

[Effectiveness of different maintenance methods for codonopsis radix].

Objective: To observe different maintenance methods including vacuum-packing, storage together with tobacco, storage together with fennel, ethanol steam and sulfur fumigation for the protection of Codonopsis Radix against mildew and insect damage, and to analyze the content of polysaccharide and flavonoids of Codonopsis Radix tested in this studies, so as to look for the scientific maintenance methods replacing traditional sulfur fumigation.

Methods: Except for the sulfur fumigation, naturally air-dried Codonopsis Radix was used to investigate the maintenance effectiveness of the above methods, respectively. Mildew was observed by visual inspection, and the content of polysaccharide and flavonoids were determined by ultra-violet and visible spectrophotometer.

[Chemical constituents from Gentiana striata].

Objective: To study the chemical constituents of Gentiana striata.

Methods: The constituents were isolated from the whole herb of Gentiana striata by recrystalization, silica gel column chromatography, polyamide column chromatography and Sephadex LH-20,etc. Their structures were elucidated through MS, 1H-NMR, 13C-NMR.

A novel member of the YchN-like fold: solution structure of the hypothetical protein Tm0979 from Thermotoga maritima.

We report herein the NMR structure of Tm0979, a structural proteomics target from Thermotoga maritima. The Tm0979 fold consists of four beta/alpha units, which form a central parallel beta-sheet with strand order 1234. The first three helices pack toward one face of the sheet and the fourth helix packs against the other face.

Refolding out of guanidine hydrochloride is an effective approach for high-throughput structural studies of small proteins.

Low in vivo solubility of recombinant proteins expressed in Escherichia coli can seriously hinder the purification of structural samples for large-scale proteomic NMR and X-ray crystallography studies. Previous results from our laboratory have shown that up to one half of all bacterial and archaeal proteins are insoluble when overexpressed in E. coli.

Conserved and nonconserved features of the folding pathway of hisactophilin, a beta-trefoil protein.

Based on previous studies of interleukin-1beta (IL-1beta) and both acidic and basic fibroblast growth factors (FGFs), it has been suggested that the folding of beta-trefoil proteins is intrinsically slow and may occur via the formation of essential intermediates. Using optical and NMR-detected quenched-flow hydrogen/deuterium exchange methods, we have measured the folding kinetics of hisactophilin, another beta-trefoil protein that has < 10% sequence identity and unrelated function to IL-1beta and FGFs. We find that hisactophilin can fold rapidly and with apparently two-state kinetics, except under the most stabilizing conditions investigated where there is evidence for formation of a folding intermediate.

pH and urea dependence of amide hydrogen-deuterium exchange rates in the beta-trefoil protein hisactophilin.

Amide hydrogen/deuterium exchange rates were measured as a function of pH and urea for 37 slowly exchanging amides in the beta-trefoil protein hisactophilin. The rank order of exchange rates is generally maintained under different solution conditions, and trends in the pH and urea dependence of exchange rates are correlated with the rank order of exchange rates. The observed trends are consistent with the expected behavior for exchange of different amides via global and/or local unfolding.