582 J. T. HOLDEN 
equal stimulatory effects are obtained with isomolal concentrations of KCl and 
sucrose”. Additionally, substances such as lysine, glucose, NH,Cl and KNO, at 
high concentrations permit large increases in accumulation capacity, whereas sub- 
stances such as glycine or glycerol, which is known to penetrate the cell rapidly, are 
inactive. In contrast to the behavior of large glutamate pools accumulated by normal 
B,-adequate cells, these pools are instantaneously lost when the cells are exposed 

- T T T T T 7 
80 + 
KCL 
7 S90. 
3 ax SS | 
VU 7 ~~. 
m 6+ if SUCROSE SS 
= J | 
8 (o) 
zs 
= 
— a 
= 40 | df =| 
< J 
—* d 
—_ y 
9 Fs 
wn 
v 
Q 20 Lf u 
a T 
i I J i [= ji 1 



0 Q2 04 06 08 10 12 14 
SUCROSE MOLALITY AND KCL OSMOLALITY 
Fig. 6. Effect of sucrose and KCl on glutamic acid accumulation by vitamin B,-deficient L. avabi- 
nosus. Cells were incubated for 100 min under standard uptake conditions modified to provide 
the indicated concentrations of sucrose or KCl. 
to dilute buffer (Fig. 7). However, the accumulation system appears to suffer no 
significant damage under these conditions since resuspension in sucrose buffer con- 
taining a fresh supply of amino acid leads to accumulation of a second large pool. 
The time of addition of glutamate to glycolizing cells has little effect on the initial 
rate of uptake suggesting that there is not a progressive degeneration of the uptake 
system in the absence of glutamate accumulation. 
It is likely that the beneficial effect of sucrose on accumulation depends on its 
ability to reduce water content in some part of the cell. The region of the cell so 

i T T ee vi 
60 + ‘GLUTAMATE AWD 06M SUCROSE 
. 
Aa | cy | 
20 | - 
moles GLUTAMATE / 100mg CELLS 



MINUTES 
Fig. 7. Effect of rapid resuspension in dilute buffer on retention of previously accumulated 
glutamic acid and reaccumulation of this amino acid by vitamin Bg-deficient L. avabinosus. 
References p. 592/594 
