mm……
'
involved was probably the breakage of hydrogen bonds followed by a collapse of the DNA
structure.,
…
-
The thermal degradation of ribonucleic acid (RNA), in contrast to DNA or protein
inactivations, has been ass0ciated with low AH* values and low or negative values for AS*.
These“ values were incompatible with a hydrogen bond breakage mechanism and it
postulated that inactivation was due to formation of a phosphotriester link,(therefore, a
'
reduCtion in degrees of freedom giving a negative value to AS*) leading to hydrolysis and
‘
ruptu‘rcbf the RNA chain at that point. Data have been reported recently showing that the
thermal inactivation of infectious ribonùcleic acid of tobacco mosaic virus was indeéd
associated with random breaking of the RNA chain.
The data of our studies on the thermal inactivation of liquid or dried suspensions of
-
measlesvirus in Parke, Davis additive (Table 4) lead to the following conclusions :
1. At moderate temperatures_(20.4° or 24.8 °C) the inactivation of liquid suspensions
"
results pr'imæily from protein dehatùration.
_
.2. At elevated temperatures. (29.49 to 37.4 °C), the inactivation of liquid suspensions
results from protein denaturation plus some breakage of the RNA chain.
_
At the… elevated temperature of 32.0. SC, the—inactivation of dried suspensions results
from breakage of the RNA chain plus some dena‘turation of protein.
'
4. At‘high‘ teniperatmeë
40;5‘°C) the inactivation of dried suspensions results
primarin from rupture of the RNA chain.
It would appear, therefore, that thethermalinactivàtion of measles virus, and presumably
—
other biologic entities, does
result from a general collapse of total structure but rather
from specic changes inspeciC components. The methods used in and the interpretation
advanced for the present studies maÿ form a basis forthe evaluation of presenyused
protective compounds and providé_Ïa 'rationale for the selection of new proteCtive
compounds.
__
,ï
»
"
;
RATES OF FREEZING AND TEMPERATURES OF THAWlNG
°
(In collaboration with our coeague, Dr.
Assistant Professor of Pathology, Marquette
University School of Medicine)
_
?
% Successful determinations of fundamental phenomena related to the effects of freezing
Ï
and freeze—drying on biologic entities are frequently a:function of the materials selected
for investigation. Althoughmeâurements
replicationcf viruses following
“
freezing and freeze-drying can be accomplished with greater precision and certainty than
î —_ î f
Qaç=evaluations of tissue .growthaor
treatment;
studies,
ezymes,.sofferi an‘ even
investigation
meuf -1aboratoes,n;has_z
ofratesoffreezmg
of thawing
25
»
—
;
Crystalline ÿëlactiQ
heart)
in -—>a »»saturated
£Ihe ;;;susp ension
f01612h0ur8 at+ 4 Cbeforeeach experlmentFurther dutwnsofenzyme005M
. phosphatebuferpH
theoh&ngëS în:
D1hydromcotmamldeAdemneD1nucleot1de(NADHz)
.
at340muatacontrolledœperatureof+ZSCwere deteedatanaldutwnof
' _
115,000 Ad1'erence Of5%maCüVywasStaüstlcallys1gmcantOneumtofenzyme
'
involved was probably the breakage of hydrogen bonds followed by a collapse of the DNA
structure.,
…
-
The thermal degradation of ribonucleic acid (RNA), in contrast to DNA or protein
inactivations, has been ass0ciated with low AH* values and low or negative values for AS*.
These“ values were incompatible with a hydrogen bond breakage mechanism and it
postulated that inactivation was due to formation of a phosphotriester link,(therefore, a
'
reduCtion in degrees of freedom giving a negative value to AS*) leading to hydrolysis and
‘
ruptu‘rcbf the RNA chain at that point. Data have been reported recently showing that the
thermal inactivation of infectious ribonùcleic acid of tobacco mosaic virus was indeéd
associated with random breaking of the RNA chain.
The data of our studies on the thermal inactivation of liquid or dried suspensions of
-
measlesvirus in Parke, Davis additive (Table 4) lead to the following conclusions :
1. At moderate temperatures_(20.4° or 24.8 °C) the inactivation of liquid suspensions
"
results pr'imæily from protein dehatùration.
_
.2. At elevated temperatures. (29.49 to 37.4 °C), the inactivation of liquid suspensions
results from protein denaturation plus some breakage of the RNA chain.
_
At the… elevated temperature of 32.0. SC, the—inactivation of dried suspensions results
from breakage of the RNA chain plus some dena‘turation of protein.
'
4. At‘high‘ teniperatmeë
40;5‘°C) the inactivation of dried suspensions results
primarin from rupture of the RNA chain.
It would appear, therefore, that thethermalinactivàtion of measles virus, and presumably
—
other biologic entities, does
result from a general collapse of total structure but rather
from specic changes inspeciC components. The methods used in and the interpretation
advanced for the present studies maÿ form a basis forthe evaluation of presenyused
protective compounds and providé_Ïa 'rationale for the selection of new proteCtive
compounds.
__
,ï
»
"
;
RATES OF FREEZING AND TEMPERATURES OF THAWlNG
°
(In collaboration with our coeague, Dr.
Assistant Professor of Pathology, Marquette
University School of Medicine)
_
?
% Successful determinations of fundamental phenomena related to the effects of freezing
Ï
and freeze—drying on biologic entities are frequently a:function of the materials selected
for investigation. Althoughmeâurements
replicationcf viruses following
“
freezing and freeze-drying can be accomplished with greater precision and certainty than
î —_ î f
Qaç=evaluations of tissue .growthaor
treatment;
studies,
ezymes,.sofferi an‘ even
investigation
meuf -1aboratoes,n;has_z
ofratesoffreezmg
of thawing
25
»
—
;
Crystalline ÿëlactiQ
heart)
in -—>a »»saturated
£Ihe ;;;susp ension
f01612h0ur8 at+ 4 Cbeforeeach experlmentFurther dutwnsofenzyme005M
. phosphatebuferpH
theoh&ngëS în:
D1hydromcotmamldeAdemneD1nucleot1de(NADHz)
.
at340muatacontrolledœperatureof+ZSCwere deteedatanaldutwnof
' _
115,000 Ad1'erence Of5%maCüVywasStaüstlcallys1gmcantOneumtofenzyme