Notes  on  Soy  Bean  Urease. 
Am.  Jour.  Pharm. 
March,  1920. 
The  greatest  activity  is  at  a  temperature  above  50°  and  probably 
below  60°.    Van  Slyke  gives  55°  as  the  optimum. 
In  comparing  the  activity  of  the  different  seed  samples,  o.i 
Gm.  of  the  powdered  sample  was  used  in  each  case,  15  Cc.  water  and 
10  Cc.  of  a  I  per  cent,  urea  solution.  After  30  minutes  in  a  bath  at 
40°,  the  mixture  was  titrated  and  a  blank  of  0.6  Cc.  deducted.  In 
addition  to  germination  tests,  nitrogen  and  moisture  were  determined 
in  the  samples.  Results  are  given  in  the  following  table.  The 
samples  were  all  of  the  19 18  crop,  with  the  exception  of  a  and  6, 
which  were  grown  in  19 14. 
TABI.E  IV. 
Seed  No. 
Variety. 
Cc. 
HCl. 
Cjcritiiii" 
ation 
%. 
Nitrogen 
%. 
Moisture 
%. 
151415 
Black  Eyebrow 
20.  2 
87 
151413 
Black  Eyebrow 
19.7 
73 
6.35 
6. 24 
151421 
Black  Eyebrow 
19. I 
80 
7.12 
6.01 
151416 
Black  Eyebrow 
19. I 
41 
6.44 
6.18 
151417 
Black  Eyebrow 
18.6 
70 
7.16 
6.36 
151412 
Black  Eyebrow 
18.5 
75 
7-49 
6.36 
163336 
Black  Eyebrow 
17. I 
61 
7.66 
6.39 
163371 
Black  Eyebrow 
17.0 
52 
7.67 
6.15 
1 63 102 
Manchu 
17.0 
92 
6.77 
5  99 
163342 
Black  Eyebrow 
16.9 
31 
7.47 
6.31 
a 
Mammoth  Yellow 
15-6 
2 
7. II 
5-97 
162806 
Minn.  109 
152 
95 
7.41 
5-51 
I 62801 
Minn.  109 
15-2 
91 
7-30 
6.15 
162804 
Minn.  109 
151 
89 
7.48 
5.60 
162905 
Minn.  1 10 
150 
75 
7.28 
5  96 
162902 
Minn,  no 
14.9 
51 
7 .02 
6.08 
151418 
Black  Eyebrow 
14.8 
82 
6.49 
6.04 
161201 
Ohio  7403 
14.2 
93 
7  50 
6.03 
161119 
Ohio  9100 
14. 1 
95 
7.91 
6.24 
161101 
Ohio  9100 
134 
92 
7-37 
6.05 
163115 
Manchu 
II-3 
87 
7  05 
5-93 
h 
Wilson 
II .  I 
23 
6.68 
6.23 
From  the  above,  it  is  evident  that  in  the  intact  seed  the  urease 
is  very  stable,  and  as  far  as  these  observations  go,  its  activity  bears 
no  relation  to  the  germinating  power  of  the  seed,  nor  to  the  nitrogen 
or  moisture  content  of  the  latter. 
Fifteen  varieties  of  soy  beans,  all  of  the  1919  crop,  were  then 
tested  in  the  same  way. 
