Divalent cation activation of flagellar ATP-phosphohydrolase from bull sperm
✍ Scribed by L. G. Young; L. Nelson
- Publisher
- John Wiley and Sons
- Year
- 1969
- Tongue
- English
- Weight
- 546 KB
- Volume
- 74
- Category
- Article
- ISSN
- 0021-9541
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✦ Synopsis
The apparently inconsistent reports on flagellar ATPase properties may be resolved by elimination of adenylate kinase from the system. Removal of the adenylate kinase from alkaline M / 2 KC1 extracts of bull sperm flagella yields a spermosin-ATPase which liberates only the terminal phosphate of ATP. In any case spermosin is preferentially activated by calcium. However, combination of spermosin with flactin (e.g., by addition of digitonin and MgClz to the extraction medium) produces an ATPase much more highly activated by magnesium. But flactospermosin has so far resisted purification from its adenylate kinase contaminant. In divalent cation activation, pH optima and nature of ATP hydrolysis, the flagellar contractile protein system closely parallels the muscle system.
Detailed examination of the biochemistry of ATP utilization as an energy source for spermatozoan motility (Engelhardt, '45; Mann, '45; Nelson, '54) reveals a number of seemingly contradictory characteristics. Utida et al. (Utida, Maruyama and Nanao, '56) found that a calcium activated ATP-phosphohydrolase of starfish sperm would hydrolyze both ATP and ADP. Bishop ('58) reported that bull sperm flagella also hydrolyzed both ATP and ADP, but the enzyme activity was magnesium dependent. Nelson, using bull sperm (Nelson, '66) and Mytilus sperm (Nelson, '55), and Mohri ('58), using sea urchin sperm, observed that these spermatozoa possessed a magnesium-activated flagellar ATPase which was specific for the terminal phosphate bond of ATP and which would not hydrolyze ADP. The ATPase which Tibbs obtained from Polytoma flagella (Tibbs, '57) was activated by magnesium and hydrolyzed both ATP and ADP, while his preparation of perch sperm flagella (Tibbs, '59) was magnesium activated and specific for the terminal phosphate bond of ATP. Brokaw ('61) showed that Polytoma flagella possess an adenylate kinase which converts ADP to ATP. An ATP-phosphohydrolase, prepared from Arbacia spermatozoa flagella by Mohri ('64) and Claybrook and Nelson ('68), was activated by both calcium and magnesium ions and was specific for the