Kinetic investigation of myeloperoxidase upon interaction with copper, cadmium, and lead ions

Myeloperoxidase [MPO], which is abundantly expressed in neutrophils, catalyzes the formation of a number of reactive oxidant species. However, evidence has emerged that MPO-derived oxidants contribute to tissue damage and initiation and propagation of inflammatory diseases, particularly, cardiovascular diseases. Therefore, studying the regulatory mechanisms of the enzyme activity is of great importance. For clarifying some possible mechanism of the enzyme activity, kinetic investigations of MPO in the presence of Copper [Cu], Cadmium [Cd], and Lead [Pb] ions were carried out in vitro. MPO was partially purified from human white blood cells using ion-exchange and gel-filtration chromatography techniques. Its activity was measured spectrophotometrically by using tetramethyl benzidine [TMB] as substrate. Purified enzyme had a specific activity of 21.7 U/mg protein with a purity index of about 0.71. Cu inhibited MPO activity progressively up to a concentration of 60 mM at which about 80% of inhibition achieved. The inhibition was non-competitive with respect to TMB. An inhibitory constant [Ki] of about 19 mM was calculated from the slope of repot. Cd and Pb did not show any significant inhibitory effect on the enzyme activity. The results of the present study may indicate that there are some places on the enzyme and enzyme-substrate complex for Cu ions. Binding of Cu ions to these places result in conformational changes of the enzyme and thus, enzyme inhibition. This inhibitory effect of Cu on the enzyme activity might be considered as a regulatory mechanism on MPO activity

Detection of Duchenne/Becker muscular dystrophy carriers in a group of Iranian families by linkage analysis

This study determines the value of linkage analysis using six RFLP markers for carrier detection and prenatal diagnosis in familial DMD/BMD cases and their family members for the first time in the Iranian population. We studied the dystrophin gene in 33 unrelated patients with clinical diagnosis of DMD or BMD. Subsequently, we determined the rate of heterozygosity for six intragenic RFLP markers in the mothers of patients with dystrophin gene deletions. Finally, we studied the efficiency of linkage analysis by using RFLP markers for carrier status detection of DMD/BMD. In 63.6% of the patients we found one or more deletions. The most common heterozygous RFLP marker with 57.1% heterozygosity was pERT87.15Taq1. More than 80% of mothers in two groups of familial or non-familial cases had at least two heterozygous markers. Family linkage analysis was informative in more than 80% of the cases, allowing for accurate carrier detection. We found that linkage analysis using these six RFLP markers for carrier detection and prenatal diagnosis is a rapid, easy, reliable, and inexpensive method, suitable for most routine diagnostic services. The heterozygosity frequency of these markers is high enough in the Iranian population to allow carrier detection and prenatal diagnosis of DMD/BMD in more than 80% of familial cases in Iran

Antioxidant effects of L-serine against fatty streak formation in hypercholesterolemic animals

Peroxidation of blood lipoproteins is regarded as a key event in the development of atherosclerosis. Evidence suggests that oxidative modification of amino acids in low-density lipoprotein [LDL] particles leads to its convert into an atherogenic form, which is taken up by macrophages. Therefore the reduction of oxidative modification of lipoproteins by increasing plasma antioxidant capacity may prevent cardiovascular disease. In this study, the antioxidant and anti-fatty streak effects of L-serine were investigated in hypercholesterolemic rabbits. Rabbits were randomly divided into three groups which were fed high-cholesterol diet [hypercholesterolemic control group], high-cholesterol + L-serine diet [treatment group], and normal diet [control] for twelve weeks and then blood samples were obtained to measure plasma cholesterol, triglyceride [TG], high-density lipoprotein [HDL], low-density lipoprotein [LDL], antioxidant capacity [AC], malondialdehyde [MDA], and conjugated dienes [CDS]. Right and left coronary arteries were also obtained for histological evaluation. No significant difference was observed in plasma cholesterol, TG, HDL, LDL and CDS levels between treatment and hypercholesterolemic control groups [P>0.05]. The levels of plasma MDA and AC were 0.29% micro M and 56%, respectively in the treatment group which showed a significant change in comparison with hypercholesterolemic control groups [P<0.05]. The mean size of produced fatty streak also showed significant reduction in the treatment group compared to the hypercholesterolemic group [P<0.05]. The results showed that L-serine has antioxidant and anti-fatty streak effects without any influence on plasma lipid levels in hypercholesterolemic rabbits