Peptidylglycine alpha amidating

07-Dec-2019 20:37 by 8 Comments

Peptidylglycine alpha amidating

The Cu SI values of plasma PAM activity were significantly higher in patients than in the control subjects.

Many of the features of Menkes disease parallel those of copper deficiency and can be explained by changes in cuproenzymes including hypopigmentation (tyrosinase) and connective tissue alterations (lysyl oxidase).We determined the concentrations of copper, the activities of ceruloplasmin and peptidylglycine α-amidating monooxygenase (PAM), and the stimulation index of PAM by the in vitro addition of copper in plasma samples obtained from three male patients with occipital horns and a milder Menkes disease phenotype, having severe copper deficiency due to the defect in copper transport.We found a decreased plasma ceruloplasmin activity and an increased copper stimulation index of plasma PAM in these patients compared with healthy control subjects.Further research is necessary to validate this point in humans because experiments using the copper-deficient rat as a model did not detect differences in stimulated serum PAM activity when excess Cu.Although the findings presented here may be valid only in a severe degree of copper deficiency, such as the unique cases of inborn error of copper transport, the data presented here are consistent with the previous observation by Prohaska, who reported that the mean Cu SI of serum PAM in marginally copper-deficient rats was more than five times higher than that in copper-sufficient controls.Erythrocyte SOD should not be responsible to acute changes in copper status because of the prolonged life time of red cells.

The assay of cytochrome c oxidase is somewhat difficult to standardize and must be performed on fresh cells.Blood samples were kept under refrigeration immediately after sampling until plasma samples were separated by centrifugation.Aliquots of plasma samples were kept at -70°C, and an aliquot from each patient was shipped from Birmingham to Duluth on dry ice for the determination of the activities of plasma PAM and ceruloplasmin.We hypothesized that these determinations are also suitable for the assessment of copper nutriture in humans, and tested this hypothesis by determining PAM activity and the Cu SI of PAM in plasma samples obtained from one family of three male patients with occipital horns and Menkes disease variant, and comparing these to the values obtained from healthy male control subjects.A Menkes disease phenotype with occipital horns is characterized by a less severe degree of neurodegeneration, growth retardation, and abnormalities of connective tissues compared with the classic Menkes disease.Therefore, it has been recognized that the development of a reliable biochemical method to assess copper nutriture in humans is necessary reported that the determination of PAM (EC 1.14.17.3) activity in serum and in heart tissue, and the stimulation of PAM by the in vitro addition of copper (Cu SI) are sensitive indicators of copper intake in the rat.