JOURNAL OF AGRIOILim RESEARCH 
Vol. XXIX Washington, D. C., November 15, 1924 No. 10 
OBSERVATIONS ON THE MECHANISM OF THE REACTION 
BETWEEN FORMALDEHYDE AND SERUM PROTEINS 1 
By R. R. Henley 
Biochemist , Biochemic Division , Bureau of Animal Industry , United States De¬ 
partment of Agriculture 
That formaldehyde effects profound 
changes in the protein molecule is, of 
course, well known, for the use of for¬ 
maldehyde as a tanning, fixing, and 
hardening agent depends upon its 
property of “ denaturing” proteins. 
One phase of its denaturing action— 
that is, the effect of formaldehyde on 
the solubilities of the proteins of blood 
serum in ammonium sulphate solu¬ 
tions—was described in a previous paper 
(4) 2 . The present paper reports the 
results of a study concerning the mech¬ 
anism of'the changes which take place 
in the proteins of formolized serums. 
In order to establish continuity with 
the preceding paper it seems desirable 
to give the following brief summary of 
the pertinent findings previously re¬ 
ported: (1) The addition of formalde¬ 
hyde to blood serum caused a progres¬ 
sive decrease in the solubility of the 
proteins in ammonium sulphate solu¬ 
tion. In that respect, the albumin be¬ 
haved as if changed to pseudoglobulin; 
the pseudoglobulin as if changed to 
euglobulin; and the native and formed 3 
euglobulins, in their turn, as if changed 
to proteins of still lower solubility. (2) 
With a given serum the rate of trans¬ 
formation was proportional to the con¬ 
centration of formaldehyde, and with 
sufficient formaldehyde proceeded to 
the complete disappearance of the al¬ 
bumin and pseudoglobulin fractions. 
(3) The addition of sufficient form¬ 
aldehyde to serum resulted in the for¬ 
mation of a gel. With given concentra¬ 
tions of formaldehyde the rapidity of 
gelatification was determined by (a) 
the concentration of the proteins and 
(b) the concentration of the salts. 
The study of the mechanism of the 
reaction by which the more soluble 
serum proteins are converted by the 
action of formaldehyde into less solu¬ 
ble forms was directed along the fol¬ 
lowing lines: (1) The effect of formal¬ 
dehyde on the precipitation limits of 
pure globulins and albumins; (2) the 
order of the reaction which results in 
the conversion of the more soluble 
proteins into euglobulins; (3) the effect 
of temperature on the velocity of the 
reaction; (4) the effect of the addition 
of formaldehyde on the titrable acid¬ 
ity; and (5) the effect of formaldehyde 
on the hydrogen-ion concentration of 
the serum. 
THE EFFECT OF FORMALDEHYDE 
ON THE PRECIPITATION LIMITS 
OF PURE GLOBULINS AND ALBU¬ 
MINS 
Schwarz (15) treated serum albumins 
and globulins with formaldehyde and 
found that the treated albumins and 
globulins were precipitated by salts 
which did not precipitate them before 
treatment. He did not undertake an 
exact study of the change which 
occurred, nor did he state the concen¬ 
tration of salts and proteins which he 
employed. In order to obtain more 
specific information the following ex¬ 
periment was made. 
EXPERIMENT I 
Euglobulins, pseudoglobulins, and 
albumins were separated as precipitates 
from a clear, normal, hog-blood serum 
1 Received for publication April 19, 1924—issued February, 1925. 
2 Reference is made by number (italic) to “Literature cited,” p. 481-482. 
2 Native euglobulins = the protein of native serum which is insoluble in one-third saturated ammonium 
sulphate solution. Formed euglobulins = the proteins insoluble in one-third saturated ammonium 
sulphate solution formed by the action of formaldehyde on the more soluble proteins. 
Journal of Agricultural Research, 
Washington, D. C. 
Vol. XXIX, No. 10 
Nov. 15, 1924 
Key No. A-79 
