Biochemical Pharmacology 

About: Biochemical Pharmacology is an academic journal. The journal publishes majorly in the area(s): Receptor & Glutathione. It has an ISSN identifier of 0006-2952. Over the lifetime, 28685 publication(s) have been published receiving 1044158 citation(s).

A new and rapid colorimetric determination of acetylcholinesterase activity.

Abstract: A photometric method for determining acetylcholinesterase activity of tissue extracts, homogenates, cell suspensions, etc., has been described. The enzyme activity is measured by following the increase of yellow color produced from thiocholine when it reacts with dithiobisnitrobenzoate ion. It is based on coupling of these reactions: The latter reaction is rapid and the assay is sensitive (i.e. a 10 μ1 sample of blood is adequate). The use of a recorder has been most helpful, but is not essential. The method has been used to study the enzyme in human erythrocytes and homogenates of rat brain, kidney, lungs, liver and muscle tissue. Kinetic constants determined by this system for erythrocyte eholinesterase are presented. The data obtained with acetylthiocholine as substrate are similar to those with acetylcholine.

Relationship between the inhibition constant (K1) and the concentration of inhibitor which causes 50 per cent inhibition (I50) of an enzymatic reaction.

Abstract: A theoretical analysis has been made of the relationship between the inhibition constant ( K I ) of a substance and the ( I 50 ) value which expresses the concentration of inhibitor required to produce 50 per cent inhibition of an enzymic reaction at a specific substrate concentration. A comparison has been made of the relationships between K I and I 50 for monosubstrate reactions when noncompetitive or uncompetitive inhibition kinetics apply, as well as for bisubstrate reactions under conditions of competitive, noncompetitive and uncompetitive inhibition kinetics. Precautions have been indicated against the indiscriminate use of I 50 values in agreement with the admonitions previously described in the literature. The analysis described shows K I does not equal I 50 when competitive inhibition kinetics apply; however, K I is equal to I 50 under conditions of either noncompetitive or uncompetitive kinetics.

Identification of an endogenous 2-monoglyceride, present in canine gut, that binds to cannabinoid receptors.

Abstract: In this study, we report the isolation from canine intestines of 2-arachidonyl glycerol (2-Ara-Gl). Its structure was determined by mass spectrometry and by direct comparison with a synthetic sample. 2-Ara-Gl bound to membranes from cells transiently transfected with expression plasmids carrying DNA of either CB 1 or CB 2 —the two cannabinoid receptors identified thus far—with K i values of 472 ± 55 and 1400 ± 172 nM, respectively. In the presence of forskolin, 2-Ara-Gl inhibited adenylate cyclase in isolated mouse spleen cells, at the potency level of Δ 9 -tetrahydrocannabinol ( Δ 9 -THC). Upon intravenous administration to mice, 2-Ara-Gl caused the typical tetrad of effects produced by THC: antinociception, immobility, reduction of spontaneous activity, and lowering of the rectal temperature. 2-Ara-Gl also shares the ability of Δ 9 -THC to inhibit electrically evoked contractions of mouse isolated vasa deferentia; however, it was less potent than Δ 9 -THC.

Spectrophotometric assay and properties of the angiotensin-converting enzyme of rabbit lung

Abstract: A sensitive, fixed-time, spectrophotometric assay for angiotensin-converting enzyme measures the rate of production of hippuric acid from hippuryl- L -histidyl- L -leucine (HHL). The angiotensin-converting enzyme from rabbit lung acetone powder extract, when assayed by this method, is optimally active at pH 8.1 to 8.3 at a chloride ion concentration of 300 mM and an HHL concentration of 5–10 mM; the K m for HHL is 2–6 mM. The enzyme was inhibited by metal-chelating agents, heavy metal salts and certain peptides. The most effective inhibitors were EDTA; CdBr 2 ; angiotensin II; bradykinin; and a pentapeptide, L -pyroglutamyl- L -lysyl- L- tryptophyl- L -alanyl- L -proline, a component of Bothrops jararaca venom. Enzyme inhibited by 0.1 mM EDTA was completely reactivated after removal of EDTA by dialysis but, after prolonged dialysis of the enzyme against 1 mM EDTA, reactivation could only be achieved by addition of metal ions: MnCI 2 (40%), ZnCl 2 (100%) or Co (NO 3 )2 (160%). The angiotensin-converting enzyme of rabbit lung is a stable, chloride ion-activated metalloenzyme, similar to both the angiotensin-converting enzyme and kininase II of plasma.

A critical evaluation of the mechanisms of action proposed for the antitumor effects of the anthracycline antibiotics adriamycin and daunorubicin

Abstract: The mechanisms responsible for the antiproliferative and cytotoxic effects of the anthracycline antibiotics doxorubicin (Adriamycin®) and daunorubicin (daunomycin) have been the subject of considerable controversy. This commentary addresses the potential role of DNA synthesis inhibition, free radical formation and lipid peroxidation, DNA binding and alkylation, DNA cross-linking, interference with DNA strand separation and helicase activity, direct membrane effects, and the initiation of DNA damage via the inhibition of topoisomerase II in the interaction of these drugs with the tumor cell. One premise underlying this analysis is that only studies utilizing drug concentrations that reflect the plasma levels in the patient after either bolus administration or continuous infusion are considered to reflect the basis for drug action in the clinic. The role of free radicals in anthracycline cardiotoxicity is also discussed.