243:
251:
673:
also play major roles in various biological processes. Although more than one form of these enzymes have been found in individual cells, these isoforms of the enzyme are unequally distributed in the various cells of an organism. From the clinical standpoint they have been found to be selectively
550:. To identify isozymes, a crude protein extract is made by grinding animal or plant tissue with an extraction buffer, and the components of extract are separated according to their charge by gel electrophoresis. Historically, this has usually been done using gels made from
482:
3.) Isoenzymes of alkaline phosphatase: Six isoenzymes have been identified. The enzyme is a monomer, the isoenzymes are due to the differences in the carbohydrate content (sialic acid residues). The most important ALP isoenzymes are
561:
All the proteins from the tissue are present in the gel, so that individual enzymes must be identified using an assay that links their function to a staining reaction. For example, detection can be based on the localised
641:), they are still among the quickest and cheapest marker systems to develop, and remain (as of 2005) an excellent choice for projects that only need to identify low levels of genetic variation, e.g. quantifying
219:. Its different regulatory features and lower affinity for glucose (compared to other hexokinases), allow it to serve different functions in cells of specific organs, such as control of
66:
genes that have diverged over time. Strictly speaking, enzymes with different amino acid sequences that catalyse the same reaction are isozymes if encoded by different genes, or
621:
is essentially a study of the causes and effects of genetic variation within and between populations, and in the past, isozymes have been amongst the most widely used
417:
2.) Isoenzymes of creatine phosphokinase: Creatine kinase (CK) or creatine phosphokinase (CPK) catalyses the interconversion of phospho creatine to creatine .
787:
Hamrick, JL, and MJW Godt. 1990. "Allozyme diversity in plant species". pp. 43–63 in A. H. D. Brown, M. T. Clegg, A. L. Kahler and B. S. Weir, eds.
59:
values), or are regulated differently. They permit the fine-tuning of metabolism to meet the particular needs of a given tissue or developmental stage.
160:) events that affect the coding sequence of the gene. As with any other new mutations, there are three things that may happen to a new allozyme:
50:
that differ in amino acid sequence but catalyze the same chemical reaction. Isozymes usually have different kinetic parameters (e.g. different
149:
and become specialised to different functions. For example, they may be expressed at different stages of development or in different tissues.
141:. However, if the mutations do not immediately prevent the enzyme from functioning, but instead modify either its function, or its pattern of
524:
184:
527:. This subtlety is to be expected, because two enzymes that differ significantly in their function are unlikely to have been identified as
507:
Isozymes (and allozymes) are variants of the same enzyme. Unless they are identical in their biochemical properties, for example their
583:
590:, which generated in zones of enzyme activity. This assay method requires that the enzymes are still functional after separation (
685:
Hunter, R. L.; Merkert, C.L. (1957). "Histochemical demonstration of enzymes separated by zone electrophoresis in starch gels".
960:
634:
714:
Weiss, B.; Hait, W.N. (1977). "Selective cyclic nucleotide phosphodiesterase inhibitors as potential therapeutic agents".
194:
In rare cases, the mutation may result in an enzyme that is more efficient, or one that can catalyse a slightly different
98:. This definition encompasses (1) enzyme variants that are the product of different genes and thus represent different
925:
Walstrom, Ford; et al. (2014). "Models of genetics and natural selection: a current biomolecular understanding".
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126:
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598:
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51:
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164:
It is most likely that the new allele will be non-functional—in which case it will probably result in low
1013:
742:
Wendel, JF, and NF Weeden. 1990. "Visualisation and interpretation of plant isozymes." pp. 5–45 in
262:
265:
is a tetramer made of two different sub-units, the H-form and the M-form. These combine in different
179:
residue that is changed is in a relatively unimportant part of the enzyme (e.g., a long way from the
198:, in which case the mutation may cause an increase in fitness, and be favoured by natural selection.
618:
543:
420:
CPK exists in 3 isoenzymes. Each isoenzymes is a dimer of 2 subunits M (muscle), B (brain) or both
216:
96:
different variants of the same enzyme having identical functions and present in the same individual
879:
The
Biology Book: From the Origin of Life to Epigenetics, 250 Milestones in the History of Biology
534:
While isozymes may be almost identical in function, they may differ in other ways. In particular,
87:
63:
794:
Biochemistry by jeremy M. Berg, John L. Tymoczko, Lubert Stryer (Intro taken from this textbook)
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Crawford, DJ. 1989. "Enzyme electrophoresis and plant systematics". pp. 146–164 in
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for this purpose. Although they have now been largely superseded by more informative
551:
188:
698:
594:), and provides the greatest challenge to using isozymes as a laboratory technique.
777:
773:
762:
758:
747:
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27:
Enzymes that differ in amino acid sequence but catalyze the same chemical reaction
757:
Weeden, NF, and JF Wendel. 1990. "Genetics of plant isozymes". pp. 46–72 in
992:
266:
208:
180:
817:
Proceedings of the
National Academy of Sciences of the United States of America
813:"Multiple forms of enzymes: tissue, ontogenetic, and species specific patterns"
499:-heat labile ALP suggests hepatitis whereas pre-β ALP indicates bone diseases.
674:
activated and inhibited, an observation which has led to their use in therapy.
659:
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535:
212:
176:
138:
122:
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to the original, then it is likely that one or the other will be lost as
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cells. Both these processes must only occur when glucose is abundant.
519:. However, such differences are usually subtle, particularly between
129:. Over evolutionary time, if the function of the new variant remains
71:
47:
575:
249:
241:
236:
587:
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567:
995:– Fatty Acid Dioxygenases and Eicosanoid Hormones (Estonia)
789:
Plant
Population Genetics, Breeding, and Genetic Resources.
866:(3rd ed.). McNaughton Publishing. pp. 413–414.
546:, and this forms the basis for the use of isozymes as
495:-heat stable ALP, pre-β ALP and γ-ALP. Increase in α
106:) and (2) enzymes that are the product of different
597:Isoenzymes differ in kinetics (they have different
955:(2nd ed.). Kolkata, India: Books and Allied.
993:Development of new isozyme specific therapeutics
989:– a complete guide to starch gel electrophoresis
145:, then the two variants may both be favoured by
78:; the two terms are often used interchangeably.
911:(6th ed.). Garland Science. p. 649.
8:
811:Markert, Clement L.; Moller, Freddy (1959).
614:Isozymes and allozymes as molecular markers
920:
918:
838:
828:
542:of the enzyme are simple to identify by
422:
271:
254:Distinction between five isozymes using
803:
62:In many cases, isozymes are encoded by
168:and be removed from the population by
574:which become insoluble when they are
7:
946:
944:
942:
940:
987:Allozyme Electrophoresis Techniques
728:10.1146/annurev.pa.17.040177.002301
117:Isozymes are usually the result of
629:-based approaches (such as direct
25:
658:isozymes play important roles in
515:, they may be distinguished by a
86:Isozymes were first described by
558:gels provide better resolution.
896:. Grady-McPherson. p. 299.
699:10.1126/science.125.3261.1294-a
635:single nucleotide polymorphisms
110:of the same gene (described as
784:Dioscorides, Portland, Oregon.
538:substitutions that change the
1:
909:Molecular Biology of the Cell
716:Annu. Rev. Pharmacol. Toxicol
207:An example of an isozyme is
183:), then the mutation may be
156:or from insertion-deletion (
137:accumulate, resulting in a
94:(1957) who defined them as
1030:
951:Satyanarayana, U. (2002).
782:Isozymes in plant biology.
767:Isozymes in plant biology.
752:Isozymes in plant biology.
592:native gel electrophoresis
402:Skeletal Muscle and Liver
379:Skeletal Muscle and Liver
215:which is not inhibited by
152:Allozymes may result from
127:nucleic acid hybridization
121:, but can also arise from
754:Chapman and Hall, London.
284:Electrophoretic Mobility
269:depending on the tissue:
44:multiple forms of enzymes
769:Chapman and Hall, London
70:if encoded by different
881:. Sterling. p. 79.
877:Gerald, Gerald (2015).
503:Distinguishing isozymes
669:The multiple forms of
333:Heart and Erythrocyte
310:Heart and Erythrocyte
258:
247:
175:Alternatively, if the
830:10.1073/pnas.45.5.753
566:of soluble indicator
293:Percentage of normal
289:Heat (at 60 °C)
287:Whether destroyed by
263:lactate dehydrogenase
253:
246:The 5 isozymes of LDH
245:
42:or more generally as
927:Biomolecular Ecology
864:Fundamental Genetics
649:Other major examples
791:Sinauer, Sunderland
693:(3261): 1294–1295.
619:Population genetics
544:gel electrophoresis
491:-heat labile ALP, α
424:
231:, or initiation of
217:glucose 6-phosphate
185:selectively neutral
892:Huang, Le (2009).
423:
259:
248:
671:phosphodiesterase
623:molecular markers
572:tetrazolium salts
548:molecular markers
523:which are often
517:biochemical assay
480:
479:
434:Tissue of Origin
415:
414:
356:Brain and Kidney
295:serum in humans
196:chemical reaction
170:natural selection
147:natural selection
16:(Redirected from
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907:Alberts (2017).
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862:Kearney (2014).
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525:neutral variants
476:Skeletal muscle
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123:polyploidisation
119:gene duplication
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513:enzyme kinetics
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261:1.) The enzyme
256:electrophoresis
223:release by the
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187:and subject to
154:point mutations
92:Clement Markert
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38:(also known as
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748:P. S. Soltis
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267:combinations
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88:R. L. Hunter
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82:Introduction
74:of the same
61:
52:
43:
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35:
32:biochemistry
29:
722:: 441–477.
278:Composition
209:glucokinase
181:active site
1003:Categories
962:8187134801
679:References
660:metabolism
556:acrylamide
536:amino acid
509:substrates
428:Isoenzyme
362:Partially
225:beta cells
213:hexokinase
177:amino acid
143:expression
139:pseudogene
64:homologous
40:isoenzymes
610:values).
580:cofactors
521:allozymes
281:Location
135:mutations
131:identical
112:allozymes
68:allozymes
971:71209231
849:16590440
799:Specific
707:13432800
582:such as
570:such as
529:isozymes
431:Subunit
405:Slowest
313:Fastest
233:glycogen
229:pancreas
203:Examples
104:isozymes
36:isozymes
18:Isozymes
1009:Enzymes
780:, eds.
765:, eds.
750:, eds.
687:Science
576:reduced
487:-ALP, α
336:Faster
227:of the
221:insulin
166:fitness
108:alleles
72:alleles
48:enzymes
969:
959:
894:Genome
847:
840:222630
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734:
705:
554:, but
462:Heart
448:Brain
46:) are
736:17360
605:and V
382:Slow
359:Fast
237:liver
158:indel
967:OCLC
957:ISBN
845:PMID
776:and
761:and
746:and
732:PMID
703:PMID
662:and
654:The
637:and
588:NADP
568:dyes
511:and
408:Yes
399:MMMM
385:Yes
376:HMMM
365:27%
353:HHMM
342:35%
330:HHHM
319:25%
307:HHHH
275:Type
100:loci
90:and
76:gene
835:PMC
825:doi
724:doi
695:doi
691:125
627:DNA
607:max
586:or
584:NAD
578:by
473:MM
467:CPK
459:MB
453:CPK
445:BB
439:CPK
411:5%
393:LDH
388:8%
370:LDH
347:LDH
339:No
324:LDH
316:No
301:LDH
125:or
114:).
30:In
1005::
965:.
939:^
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917:^
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833:.
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34:,
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827::
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697::
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603:M
600:K
497:2
493:2
489:2
485:1
483:α
469:3
455:2
441:1
395:5
372:4
349:3
326:2
303:1
191:.
172:.
56:M
53:K
20:)
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