120
mam—ww
,
Solutions at high dilution (l : 15,000), cdoled at 70 °C/min. to a terminal temperature
of — 70 °C and thawed at + 10 °C lost 64 % of their activities; at + 20 °C, 58 %; at + 30°;
+ 50° or + 100 °C, the average loss was 50 %. Differences in the levels of activities were
not signicant in solutions‘ot‘ enzyme (l : 15,000) cooled at 1 °C/min. to et termina] temperature of —— 70 ÔC and thawed as the above; the loss in activities averaged 65 %.
It is frequently stated that freezing slowly is less detrimental to biologic materials than;
freezing rapidly. If one_ aSSumes a relationship, in rapidly agitated samples, between
temperatures of thawing and rates of thawing, our data indicate that the effects of rates
of freezing are uneertain;üress characterized in relatiOn to the rates of thawing and
'
the active
of the system. The effects of .freezing slowly
(l
freezing rapidly (70
protein materials at high concentration
can be compared only if the frozen solutions are thawed rapidly (+ 100 èC); at low
concentration Only if thaWed slowly (+ 10 °C). When the nature Or mass of the
pfeèlÿdes rdpid;rates of
would appear desirable to freeze by cooling
slowlyÿ, (Z,
,
°C/mm) to mininiize variatiohsin activities reSulting‘from derent rates of thawz‘ng
'
throuäôüt—‘ the material; f"
ï
‘
Ï
REHYDRATION‘ (PRELÏMINARY STUDIES)
Because water is the-component usually
materials or systems are
.
dried”by sublimation inŸ vaCùà, it*is the usual practibe-tb rehydrate With”Water. The data
of our studies on the freeze-drying of
”indicated that the compound
used for rehydration were most important for the retention of activity by dried and reconstituted suspensions of mitochondria. In-general, these compounds were of high molecular
weight and soluble in water and in solutions of sucrose or
also that
the method ofpreparationot‘ the material could be evaluated for e”ect on the total process
after. drying; and rehydration,
highest retention
activities in mitochondria
% dextran
rchydraüng. media-Because of
of solutions of
highmolæular weight…compdunds, it is
these solutions; act in
by regulatin—gthe rate at which water
enters the
may? also prevent the migration
of dried components during the rehÿdration process.;…
_
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:
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.
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.
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mam—ww
,
Solutions at high dilution (l : 15,000), cdoled at 70 °C/min. to a terminal temperature
of — 70 °C and thawed at + 10 °C lost 64 % of their activities; at + 20 °C, 58 %; at + 30°;
+ 50° or + 100 °C, the average loss was 50 %. Differences in the levels of activities were
not signicant in solutions‘ot‘ enzyme (l : 15,000) cooled at 1 °C/min. to et termina] temperature of —— 70 ÔC and thawed as the above; the loss in activities averaged 65 %.
It is frequently stated that freezing slowly is less detrimental to biologic materials than;
freezing rapidly. If one_ aSSumes a relationship, in rapidly agitated samples, between
temperatures of thawing and rates of thawing, our data indicate that the effects of rates
of freezing are uneertain;üress characterized in relatiOn to the rates of thawing and
'
the active
of the system. The effects of .freezing slowly
(l
freezing rapidly (70
protein materials at high concentration
can be compared only if the frozen solutions are thawed rapidly (+ 100 èC); at low
concentration Only if thaWed slowly (+ 10 °C). When the nature Or mass of the
pfeèlÿdes rdpid;rates of
would appear desirable to freeze by cooling
slowlyÿ, (Z,
,
°C/mm) to mininiize variatiohsin activities reSulting‘from derent rates of thawz‘ng
'
throuäôüt—‘ the material; f"
ï
‘
Ï
REHYDRATION‘ (PRELÏMINARY STUDIES)
Because water is the-component usually
materials or systems are
.
dried”by sublimation inŸ vaCùà, it*is the usual practibe-tb rehydrate With”Water. The data
of our studies on the freeze-drying of
”indicated that the compound
used for rehydration were most important for the retention of activity by dried and reconstituted suspensions of mitochondria. In-general, these compounds were of high molecular
weight and soluble in water and in solutions of sucrose or
also that
the method ofpreparationot‘ the material could be evaluated for e”ect on the total process
after. drying; and rehydration,
highest retention
activities in mitochondria
% dextran
rchydraüng. media-Because of
of solutions of
highmolæular weight…compdunds, it is
these solutions; act in
by regulatin—gthe rate at which water
enters the
may? also prevent the migration
of dried components during the rehÿdration process.;…
_
…
:
'
.
……—
on
=of«monovalent
.
ECHO
ta elevated
'i‘f
_
'
_
bv
'
IMMgC12 wasoutstandmg 25hours at 50€; 3
25daysaîatçrgomtemperature
.
and at
3monthsat4°C
.
‘
of
several parts,;oÿ theÏJ
,
'
necessary toretamthestructural 1ntegry0fthewusTheenzymeamylasehasbeen
«
shownalsotabestablmedhytheaddwnofd1valentcalwmwnsIthasbeenpropoæd
thatsaüonsmmgholarcencentratwnpermeaævmusparüclesandremforcestruetures
"? Ï
»
aunug:heatstœssandthattheenzymelsprotectedfromdenaturaüon0fproîembya '