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抗凍基因(antifreezing gene)

(4)抗凍蛋白分子的抗凍活性與抗凍蛋白溶液濃度的定量關係
的理論計算結果與實驗結果符合。
(5)對於分子量較大的抗凍蛋白，例如Type II AFPs，其一個
分子在冰晶表面的吸附中心數與蛋白的合作數幾乎相等；對於
分子量較小的抗凍蛋白，例如Type I AFPs，其蛋白的合作數
要大於一個蛋白分子在冰晶表面的吸附中心數，說明大分子量
的抗凍蛋白具有較多的吸附中心。 對於分子量較小的抗凍蛋
白分子溶液，即使濃度相同，溫度較低時的抗凍活性要低於溫
度較高的抗凍活性，要求的抗凍蛋白合作數也增加。因此，當
濃度較低時它們將失活去活性。隨著濃度的增加，各種抗凍蛋
白的活性都將達到飽和。 分子量較大的抗凍蛋白的吸附常數
Kt遠大於分子量較小的抗凍蛋白的吸附常數，說明大分子量的
抗凍蛋白具有較強的與冰晶表面結合的能力。
生物技術概論(高立圖書)
第十章
10-1
Structural Characteristics of the Antifreeze
Proteins (AFP) and Glycoproteins (AFGP)
Character
istic
Molecular
Mass
Natural
Source
AFGP
AFP Type I
2,600 - 33,000
3,300 - 4,500
Antarctic notothenioids;
Northern cods
(Atlantic cod,
Greenland cod)
right-eyed flounders
(winter flounder);
sculpins
(shorthorn)
生物技術概論(高立圖書)
第十章
AFP Type II
AFPe
Type3
AFPe
Type IV
11,000 24,000
6,500
12,229
Ocean
pout;
wolffish
Longhorn
sculpin
sea raven;
smelt;
herring
10-2
Fish antifreeze proteins - applications
In years to come, blood products may be stored for longer periods of time, a therapy for
hypothermia may be developed, and a salmon with superior growth capabilities may
become standard.
Study cold water adaptation in fish with an emphasis on the antifreeze proteins found in
their blood. These vital proteins prevent ice crystals from growing in the blood when
the water temperature is very low, thus preventing the fish from freezing.
Atlantic salmon do not possess antifreeze proteins and therefore are unable to be
cultured in sub-zero waters off the Atlantic coast of Canada. In order to make salmon
more freeze resistant, Dr. Fletcher injected antifreeze protein genes into salmon eggs.
These genes were incorporated into the salmon's chromosomes and so far they have
passed on through three successive generations of salmon.
However, as Dr. Fletcher explained, "The levels of antifreeze found in the salmon are
low; thus, although the results are promising, more research is required before this
salmon broodstock will be of value to industry."
This is not the only research ongoing to improve the performance of salmon for
aquaculture. In 1990 Dr. Fletcher and his colleague, Dr. Choy Hew of the University of
Toronto, developed a gene that contained a salmon growth hormone and antifreeze
component. When Dr. Fletcher's team injected this gene into the salmon eggs, the
resulting transgenic salmon grew four to six times faster than standard salmon.
生物技術概論(高立圖書)
第十章
10-3