Nickel affects xylem Sap RNase a and converts RNase A to a urease

BMC Plant Biology

Table 2 Ureolytic activity of purified pecan xylem sap RNase A compared to that of jack bean urease and bovine pancreatic RNase A

Sample	Activity (Unit/ml)^a	Specific activity (Unit/mg protein)^a
Purified bovine pancreatic RNase A (13.4 kDa)	179.9 ± 15.7	179.9 ± 15.7
Purified jack bean urease (590 kDa)^b	589.0 ± 64.1	589.0 ± 64.1
Crude xylem sap proteins	24.93 ± 2.04	80.41 ± 6.56
Purified xylem sap 14 kDa protein	371.25 ± 17.33	222.75 ± 10.44
Buffer control	0	0

^aActivity and Specific Activity is mean values (± SD) of three replicate assays; urease catalyzes the hydrolysis of urea to ammonia and carbon dioxide.
^bThe molecular mass for native jack bean urease is from 480 kDa to 590 kDa¹³ and calculated size is about 540 kDa for the hexamer.

ISSN: 1471-2229