ROUND TABLE DISCUSSION 773, 
on glycolysis. In the case of oligosaccharides, evidence that K* ions are also required and that Nat 
ions are inhibitory was set forth in published reports.* A K+ requirement for metabolically de- 
pendent penetration of short chain monocarboxylic aliphatic anions has also been observed. 
This is illustrated with propionate, butyrate, and valerate in Fig. 3. The same results were ob- 
tained with formate and acetate. The failure of metabolic penetration in the presence of Na* 
(0.55 M) can be overcome by addition of small quantities of Kt (e.g. 0.01 M). With appropriate 
levels of Nat and K+ ions, it turns out that the rate of metabolic penetration is a function of the 
carbon chain length, the rate decreasing with increasing chain length. 
Of interest also is the marked difference between the behaviour of monocarboxylate anions and 
chloride as shown in Fig. 4. Glycolysis seems to have no effect on the penetration of KCI while 
K formate penetrates rapidly. In a like manner, glycolysis appears to have no effect on the pene- 
tration of NaCl. 
HENDLER: This has bearing on a point raised by Dr. ANDERSON, as to what could bind the amino 



1.0 
ee 
eS 
50.8 
> Propionate 
= ‘ Buty rate srmenem 
N Valerate -——— 
006 
a 
< 
° 
i 
100 
5 
MINUTES 
Fig. 3. The effect of glycolysis, K+ and Nat on protoplasts stabilized with proprionate, butyrate 
and valerate. Protoplasts of S. faecalis previously depleted of K+ were osmotically stabilized in 
solutions of salts of monocarboxylic acids (0.4 MM) containing phosphate (0.075 M, pH 7.2). The 
cations were either all K+ or all Nat as indicated on the curves. Glucose (0.01 /) was added at 
the time shown by the arrow. The rate of swelling during glycolysis, observed photometrically, 
indicates that the rate of penetration of the K salts during glycolysis becomes very rapid while 
the penetration rate of the Na salt remains unchanged. The substitution of Na* for K* does not 
alter the initial rate of glycolysis as measured by continuous titration of acid production at 
constant pH (pH stat). 
acid in sufficient quantity. Dr. CHRISTENSEN raised the question whether in view of the tremendous 
amounts of intracellular amino acid there are sufficient sites for them. Dr. Cowir was saying that in 
his system perhaps protein or nucleic acid might have sufficient surface. But in those experiments 
I reported yesterday, where attempts were made to dilute the specific activity of a small quantity 
of radioactive valine with a rather large quantity of unlabeled valine, it was found that the mono- 
molecular site I talked about with respect to amino acid did not give any indication of approach- 
ing saturation after the tremendous quantity of 200 mg unlabeled valine were added. The total 
volume was about g ml, including external medium and tissue, and there was a linear amount of 
total radioactive valine which was held in the lipid-soluble form as opposed to the water-soluble 
form (as a function of added valine), so that there was a capacity for holding valine in a form 
which altered its solubility and was able to handle tremendous quantities of valine and gave no 
indication of approaching saturation even out of this high level. 
REINER: Before we get too far from Dr. ABRAMS’ remarks I would like to point out their relevance 
to what we were discussing before; that is, the experimental evidence for binding. This seems to be 
one of a number of pieces of evidence that indicate that for studying the binding of amino acids to 
cell components, the composition of the medium is extremely critical, and it is impossible to decide 
whether your experiments are successful until a lot of work has been done just along these lines. 
What is the optimum medium for studying binding, if there is any binding? There is a lot of 
other evidence available, but I don’t think it is necessary because Dr. ABRAMS’ experiments are 
about as dramatic evidence as you could ask for. 
HeErnz: I am not quite satisfied with the explanation given, for instance for the swelling and the 
References p. 777 
