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wjl215

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Enzymes may be immobilized by a variety of methods,
which may be broadly classified as physical, where weak interactions
between support and enzyme exist, and chemical,
where covalent bonds are formed with the enzyme.
To the physical methods belong: (i) containment of an enzyme
within a membrane reactor, (ii) adsorption (physical,
ionic) on a water-insoluble matrix, (iii) inclusion (or
gel entrapment), (iv) microencapsulation with a solid membrane,
(v) microencapsulation with a liquid membrane, and
(vi) formation of enzymatic Langmuir-Blodgett films. The
chemical immobilization methods include: (i) covalent attachment
to a water-insoluble matrix, (ii) crosslinking with
use of a multifunctional, low molecular weight reagent, and
(iii) co-crosslinking with other neutral substances, e.g. proteins.
Numerous other methods which are combinations of
the ones listed or original and specific of a given support
or enzyme have been devised. However, no single method
and support is best for all enzymes and their applications.
This is because of the widely different chemical characteristics
and composition of enzymes, the different properties of
substrates and products, and the different uses to which the
product can be applied. Besides, all of the methods present
advantages and drawbacks. Adsorption is simple, cheap and
effective but frequently reversible, covalent attachment and
crosslinking are effective and durable, but expensive and
easily worsening the enzyme performance, and in membrane
reactor-confinment, entrapment and microencapsulations
diffusional problems are inherent. Consequently, as a
rule the optimal immobilization conditions for a chosen enzyme
and its application are found empirically by a process
of trial and error in a way to ensure the highest possible
retention of activity of the enzyme, its operational stability
and durability.

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fayebest7783

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wjl215(金币+3,VIP+0):有些地方翻译不够专业术语，不过很感谢。 9-19 19:31
zap65535(金币+3,VIP+0):苦劳奖 12-22 13:00

酶的固定也许有很多种方法，这些方法可以广义地划分为物理和化学方法，其中物理方法中载体和酶之间的相互作用很弱，而化学方法中则形成共价键。属于物理方法的有（1）膜反应器内酶的抑制法（2）在水溶性基质上的吸收（物理的，离子的）（3）包埋法（胶体诱导法）（4）微胶囊膜法（5）成L-B薄膜法。化学固定方法有以下几种：（1）在水溶性基质上的共价附着（2）用多功能低分子量的反应剂交联法（3）同其他中性物质入蛋白质等的共交联法.还有多种方法或者新颖独特的载体或者酶已经被设计出来，这些方法是将上面列举出来方法加以整合而得到的.然而，没有一种方法和载体对所有的酶都能很好地适用。这归因于酶的成分和化学特性有很大不同，底物和产物的不同性质以及产物的用途不同等。此外，所有的方法都存在优缺点。吸附法简单有效而且廉价但是常存在反应可逆的问题，共价附着和交联法高效且持久耐用，但是昂贵且很容易降低酶的性能，而且膜反应器内抑制法，诱导法以及微包覆法中存在扩散问题。因此，对于给定的酶来说，只能通过经验或者反复试验来最大限度地保持酶的活性，操作上的稳定性和持久耐用性等。