Digestion of chromatin in nuclei by micrococcal nuclease, measured as the change in the concentration of monomer-length DNA with time, displays Michaelis-Menten kinetics. Redigestion of soluble chromatin prepared from nuclei by micrococcal nuclease treatment, however, is apparently first order in enzyme and independent of chromatin concentration. This qualitative difference results from an incr...

Nucleoside diphosphate kinase (NDPK), as a house-keeping protein, involves in various molecular processes including signal transduction, energy and drug metabolism. The main objective was to investigate NDPK kinetics in human erythrocytes and to monitor the frequency distribution of NDPK activity levels in Chinese healthy subjects and transplant recipients. METHODS: NDPK activity in erythrocyte...

Recent measurements of natural populations of the marine cyanobacterium Prochlorococcus indicate this numerically dominant phototroph assimilates phosphorus (P) at significant rates in P-limited oceanic regions. To better understand uptake capabilities of Prochlorococcus under different P stress conditions, uptake kinetic experiments were performed on Prochlorococcus MED4 grown in P-limited che...

Chlorpyrifos (CPF) and diazinon (DZN) are thionophosphorus organophosphate (OP) insecticides; their toxicity is mediated through CYP metabolism to CPF-oxon and DZN-oxon, respectively. Conversely, CYPs also detoxify these OPs to trichloropyridinol (TCP) and 2-isopropyl-4-methyl-6-hydroxypyrimidine (IMHP), respectively. In addition, A-esterase (PON1) metabolism of CPF- and DZN-oxon also forms TCP...

principle, lead to depletion of VIP in the airways and abnormalities characteristic of asthma. To examine whether catalytic antibodies can evolve over the normal course of antibody affinity maturation, we prepared monoclonal antibodies by immunization with a VIP-carrier protein conjugate. One of these antibodies hydrolyzed VIP with Km (Michaelis-Menten constant) 0.34 nM and turnover 8X10-4/min....

Prostatic acid phosphatase (EC 3.1.3.2) purified from benign hypertrophic prostate tissue was fractionated by preparative slab isoelectric focusing over a pH gradient of 3.16 to 7.16. Twenty-two of 29 fractions contained enzyme activity. We further examined each active fraction by determining the Michaelis-Menten constant and specific activity. The protein concentration used in the latter deter...

The kinetics of hepatic indocyanine green (ICG) uptake have been analysed in 14 patients with chronic active liver disease. The removal of incremental, submaximal ICG doses were compatible with Michaelis-Menten kinetics in approximately 80% of studies in patients allowing the calculation of the maximal rate of removal (Rmax) and the Michaelis constant (Km). Neither of these variables correlated...

The phenomenon of plasma renin activattion by acid dialysis and preincubation with trypsin was studied in normal human plasma. Activation of plasma renin by exposure to pH 3.3 was shown to require at least one dialysis step and could be inhibited by the presence of Trasylol, indicating the involvement of a protease in acid activation. Amniotic fluid exposed to pH 1.5 to destroy renin and renin ...

1. The uptake of bilirubin was studied in the perfused rat liver by a multiple-indicator dilution technique employing the three-compartment model of Goresky. 2. The kinetics of hepatic bilirubin uptake could be described by the Michaelis-Menten equation. 3. The maximal uptake velocity (V max.) and the apparent half-saturation constant (Km) were 4-4 +/- 0-5 nmol s-1 g-1 of liver and 58 +/- 16 nm...

Gold nanoparticles (AuNPs) have been self-assembled onto electrochemically deposited polyaniline (PANI) films on indium-tin-oxide (ITO) coated glass plates to fabricate glucose biosensor. The covalent immobilization of glucose oxidase (GOx) in the near vicinity of gold nanoparticles has been obtained using N-ethyl-N'-(3-dimethylaminopropyl) carbodiimide (EDC)/N-hydroxysuccinimide (NHS), chemist...