|
KMID : 0365819740140020213
|
|
Journal of Pusan Medical College
1974 Volume.14 No. 2 p.213 ~ p.219
|
|
|
The Maximum Ca^(++) Binding Capacity of Human Erythrocyte Membrane Fragments
|
|
|
|
|
Abstract
|
|
|
A small amount of human RBC fragments (0.3mg) were dried on a cover glass and incubated in a various concentration of Ca-(with Ca"). Then, the cover glass was taken out and washed several times by dipping in a large volume of 2 mM Tris buffer (pH 7.4). The radioactivity remaining in cover glass was counted, and the amount of Ca" bound to the RBC membrane fragment was calculated. The maximal Ca" binding capacity was also studied after lipid extraction, titration of COOH with carbodiimide and titration of SH with PCMB of the RBC membrane fragments. The results were summarized as follows.
1. The maximal Ca" binding capacity in normal fragments was found to be 498 μmoles/g protein, This value was obtained at Ca" concentration over 30 mM in medium.
2. The maximal Ca" binding capacity in lipid extracted RBC membrane fragments by chloroformmethanol mixture was found to be 306 μmoles/g protein, and this value corresponded to 61% of the maximal binding capacity of normal RBC fragment. Consequently, the maximal binding capacity to lipid fraction of RBC corresponded to 39% of the total binding capacity.
3. The maximal Ca" binding capacity of the RBC membrane fragments was reduced to 49.5 μmoles/g protein after the RBC fragments were subjected to the lipid extraction and titration of COOH by carbodiimide treatment. This value showed about 9% of the total Ca" binding capacity of norn a1 RBC membrane fragments.
4. The maximal Ca´ binding capacity was reduced to 45. 1 μmoles/g protein after RBC membrane fragments were subjected to lipid extraction, COOH titration, and SH titration by PCMB. The effect of PCMB was reversed by an addition of cysteine in the incubation medium. This result indicates that Ca" binding to SH radical is almost negligible compared to the other binding sites(or radicals).
|
|
|
KEYWORD
|
|
|
|
|
|
FullTexts / Linksout information
|
|
|
|
|
|
Listed journal information
|
|
|
|
|