Mapping and analysis of protein sulfhydryl groups by modification with 2-bromoacetamido-4-nitrophenol

A method for identifying cysteine-containing peptides in proteins is presented using 2-bromoacetamido-4-nitrophenol (BNP) to introduce an easily detectable probe. The formation of a covalent bond between the protein sulfhydryl group and the acetamido moiety of BNP introduces a chromophore with an absorbance maximum at 410 nm. The modified protein can then be cleaved with appropriate proteases and the resulting peptides separated by chromatographic methods. Monitoring the effluent at a single wavelength (405 nm) provides a rapid and simple method of detecting and isolating only those peptides which contain cysteine residue(s). The nitrophenol derivative is stable under conditions required for protease cleavage. The reagent is therefore useful for locating cysteine-containing peptides in protein digests and can be used to explore the accessibility of different cysteines under a variety of conditions. The ease of modification, specificity of reaction, product stability, and simple detection of modified peptides make BNP ideal for investigation of cysteine residues.     

Comparison of Karanjin with other nitrification inhibitors for retardation of nitrification of urea N in soil

Summary Comparative evaluation of Kranjin and three patented nitrification inhibitors for retardation of nitrification of urea in a sandy clay loam showed that the effectiveness of the compounds tested decreased in the order: Nitrapyrin>Karanjin>A.M.>dicyandiamide.     

Preparation of chloroplast DNA from pea plastids isolated in a medium of high ionic strength

A simple, rapid, and inexpensive method for the preparation and purification of chloroplast DNA (cpDNA) from pea has been developed. The crucial step is the isolation of chloroplasts in a medium of high ionic strength (I congruent equal to 1.40 M). CpDNA from pea prepared according to this method has successfully been used for restriction enzyme mapping, Southern transfers, and cloning.     

Evaluation of laser-Doppler perfusion imaging for measurement of blood flow in cortical bone.

Most techniques currently available to measure blood flow in bone are time consuming and require destruction of the tissue, but laser-Doppler technology offers a less invasive method. This study assessed the utility of laser-Doppler perfusion imaging (LDI) to measure perfusion in cortical bone. Twelve mature New Zealand White rabbits were assigned to one of three groups: normal control, constriction (norepinephrine), or dilatation (nitroprusside). The left and right medial tibiae were consecutively scanned at red (634-nm) and near-infrared (810-nm) wavelengths to examine the repeatability of LDI output. The pharmacological intervention groups were injected with the respective drug, and LDI measurements at 810 nm were obtained concurrently with colored microsphere-determined flow in all of the groups. LDI effectively quantified blood flow in cortical bone and detected physiologically induced changes in perfusion. A significant positive correlation was found between microsphere-determined flow and LDI output (r = 0.6, P < 0.05). Repeatability of consecutive LDI measurements was within 5%. The effectiveness of LDI to measure perfusion in bone suggests this method has potential for investigating the role of blood flow in bone metabolism and remodeling.