| Summary: | 碩士 === 國立清華大學 === 輻射生物研究所 === 81 === Two modifying reagent, N-bromosuccinimide (NBS) an d
2-hydroxy-5-nitrobenzyl bromide (HNBB), could inhibi t the
hydrolysis activity of tonoplast ATPase from eti olated mung
bean. Under our condition, HNBB is specifi c for the
modification of tryptophan, while NBS could react with several
residues besides tryptophan. the in activation of ATPase by
HNBB was concentration- and ti me-dependent. From the
semilogarithmic plot of time co urse of the inactivation, the
reaction order of inacti vation was calculated as 0.973,
indicating that at lea st one tryptophan was esstential to the
enzymatic acti vity of V-ATPase. Kinetic analysis shows that Km
but n ot Vmax of ATPase was changed by NBS, while the Vmax b ut
not Km of the enzyme was decreased by HNBB. ATP and its analogs
could protect ATPase against NBS but not H NBB, implying that
modification sites of NBS and HNBB are not same.
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