Purification and properties of a novel nucleotide-hydrolysing enzyme (5′-nucleotidase) from Boophilus microplus

Abstract

The tick Boophilus microplus contains a nucleoside phosphate-hydrolysing enzyme which, in many respects, resembles the well characterized 5'-nucleotidase from mammalian tissue. The tick enzyme has been purified to homogeneity. It is a membrane-bound glycoprotein with an apparent Mr of 67,000 and, although it fails to hydrolyse a range of nucleoside 2'- or 3'-monophosphates, it has broad specificity for the 5' derivatives. Further investigation of the enzyme's substrate specificity, however, shows some important differences from the mammalian nucleotidases. It hydrolyses both bis-p-nitrophenyl phosphate and p-nitrophenyl phenylphosphonate, typical substrates for phosphodiesterases. However, the tick enzyme is most strikingly different from the mammalian enzymes in that it hydrolyses not only AMP but ADP and ATP as well. Further, the products of the hydrolysis of ATP are adenosine and tripolyphosphate, a reaction which has not been reported previously. The products of ADP hydrolysis are adenosine and pyrophosphate.

Tick anti-hemostatics: targets for future vaccines and therapeutics

“…To date, only partial sequences for putative apyrases have been described for I. scapularis [6], Argas monolakensis (GenBank ABI52806) and O. savignyi (C. Stutzer, MSc thesis, University of Pretoria, 2007), indicating that they are members of the 5 0 -nucleotidase or CD73 family [6]. A 5 0 -nucleotidase enzyme from B. microplus hydrolyzes both ATP and ADP [43], although its effect on platelet aggregation and adhesion remains to be confirmed. Expression library immunization (ELI) with the putative nucleotidase from I. scapularis showed a 50% reduction in tick infestation [44].…”

Bioactive Compounds in Tick and Mite Venoms (Saliva)

“…Enzymes present in the saliva of the cattle tick, Boophilus microplus, are glycosidases and proteases. 5 -Nucleotidase is present in the venom of Boophilus microplus and its molecular weight is 67 kD (Willadsen et al, 1989). The exact function of tick enzymes is not known, but it is speculated that it may be involved in some kind of function in a victimized host (Kerlin and Hughes, 1992).…”

Experimental vaccination of sheep and cattle against tick infestation using recombinant 5′-nucleotidase

“…The 5′-nucleotidase from R. (Boophilus) microplus would seem to have potential in the ‘concealed antigen’ approach to vaccination ( 3 ). The purification and characterization of the native protein have been previously reported ( 4 , 5 ;). Among the characteristics likely to be of importance for ‘concealed antigens’ are accessibility to antibody ingested during tick feeding and a physiological function of importance to the tick.…”