2076
PAULH. MAURERAND MICHAEL HEIDELBERGER
VOl. 73
less tendency to aggregate than DnEa, in agreement with the viscosity data.
1.4 1.2
TABLE IV EFFECT OF SODIUM CHLORIDE SOLUTIONS ON VARIOUS DENATURED PREPARATIONS. PER CENT. PROTEIN PRECIPITATED, 1 HR., 37’
c
.*
ec 1.0
c
2P 0.8 M
026
05
1.0
M
M
M
1.5 M
5A U a a a 5A Dn a a a b Acid DnEa 105 a b b 57 8B Dn a a b 31‘ Heat Dn 27 b b 63 88 Clear solution. Opalescent solution. opalescent after centrifugation.
Ln
2. 9 0.6
-,-
-
0
c
0.4 .-0
2
20 M
25 M
63 76 72 99 69 88 94 98 Supernatant b 24‘
0.2
9. Binding of Methyl Orange.-The extent of binding of the anion of methyl orange by approximately 0.2% protein solutions was measured a t pH -6.0 -5.5 -5.0 -4.5 -4.0 6.8 by differential dialysis.36 The samples were Log (methyl orange) free. dialyzed against dye solutions ranging in concenFig. &-Methyl orange bound by DnEa and deaminated to 8.40 X 10-6 M. tration from 0.165 X Ea fractions-key to chart: 0 DnEa 105, 6 DnEa 105 The results are summarized in Fig. 4. Neither Deam-SH, 0 5A, X 5A Dn, + 8B Dn. Ea nor 8B bound dye, but DnEa did, in agreement in Table IV. Here, too, a definite difference is with results and statements of others.a7 When acid DnEa is deaminated, it has a reduced shown between acid DnEa and heat DnEa on the one hand, and an A fraction on the other. In 1.5 binding ability similar to that of the A and ADn N NaCl solution the A fraction remains soluble preparations. 8BDn, which can be considered whereas the DnEa preparations precipitate to the in a sense “isomeric” with deaminated DnEa, extent of 60y0. This would indicate that the A binds less than DnEa and more than its deaminated fraction does not exist in a form as fully extended form. I t is difficult to decide what part in these or as subject to aggregation as the other DnEa relationships is played by the decrease in cationic preparations, in accord with the nitroprusside nitrogen and what part is due to differences in tests and the particle weights. In its salt sensi- molecular configuration. tivity, also, fraction 6ADn appeared to be more ( 3 6 ) I M Klotz, F M Walker and R R Piven THEJ O U R N A I , 68, unfolded or aggregated than 5A. Whexeas 5A4 1486 (1946) (37) I M KloLz and J. M Urquhdrt. rbtd, 71 1597 (1949). was opalescent in 2.0 izI NaC1, 5ADn precipitated to the extent of 24%. Acid denatured 8 R showed ?;E\\ YOKK,K Y. RECEIVED J U L Y 11, 1
