Proton inventories constitute reliable tools in investigating enzymatic mechanisms: Application on a novel thermo-stable extracellular protease from a halo-alkalophilic Bacillus sp.
Φόρτωση...
Ημερομηνία
Συγγραφείς
Theodorou, L. G.
Perisynakis, A.
Valasaki, K.
Drainas, C.
Papamichael, E. M.
Τίτλος Εφημερίδας
Περιοδικό ISSN
Τίτλος τόμου
Εκδότης
The Japanese Biochemical Society
Περίληψη
Τύπος
Είδος δημοσίευσης σε συνέδριο
Είδος περιοδικού
peer reviewed
Είδος εκπαιδευτικού υλικού
Όνομα συνεδρίου
Όνομα περιοδικού
J Biochem
Όνομα βιβλίου
Σειρά βιβλίου
Έκδοση βιβλίου
Συμπληρωματικός/δευτερεύων τίτλος
Περιγραφή
A novel protease designated protease-A-17N-1, was purified from the haloalkalophilic Bacillus sp. 17N-1, and found active in media containing dithiothreitol and EDTAK(2). This enzyme maintained significant activity from pH 6.00 to 9.00, showed optimum k(cat)/K-m value at pH 7.50 and 33 degrees C. It was observed that only specific inhibitors of cysteine proteinases inhibited its activity. The pH-(k(cat)/K-m) profile of protease-A-17N-1 was described by three pK(a)s in the acid limb, and one in the alkaline limb. Both are more likely due t3o the protonic dissociation of an acidic residue, and the development and subsequent deprotonation of an ion-pair, respectively, in its catalytic site, characteristic for cysteine proteinases. Moreover, both the obtained estimates of rate constant k(1) and the ratio k(2)/k(-1) at 25 degrees C, from the temperature-(k(cat)/K-m) profile of protease-A-17N-1, were found similar to those estimated from the proton inventories of the same parameter, verifying the reliability of the latter methodology. Besides, the bowed-downward proton inventories of k(cat)/K-m, as well as the large inverse SIE observed for this parameter, in combination with its dependence versus temperature, were showed unambiguously that k(cat)/K-m = k(1). Such results suggest that the novel enzyme is more likely to be a cysteine proteinase functioning via a general acid-base mechanism.
Περιγραφή
Λέξεις-κλειδιά
cysteine proteinases, enzyme kinetics, enzyme mechanisms, halo-alkalophiles, proton inventories, papain-catalyzed hydrolyses, cysteine proteinases, active-site, inhibitor, electrophoresis, purification, peptidases, dependence, kinetics, insight
Θεματική κατηγορία
Παραπομπή
Σύνδεσμος
<Go to ISI>://000251645900017
http://jb.oxfordjournals.org/content/142/2/293.full.pdf
http://jb.oxfordjournals.org/content/142/2/293.full.pdf
Γλώσσα
en
Εκδίδον τμήμα/τομέας
Όνομα επιβλέποντος
Εξεταστική επιτροπή
Γενική Περιγραφή / Σχόλια
Ίδρυμα και Σχολή/Τμήμα του υποβάλλοντος
Πανεπιστήμιο Ιωαννίνων. Σχολή Θετικών Επιστημών. Τμήμα Χημείας