Causas epistemológicas, político-administrativas

55

1 Ka

1

1

IV

. v = v

C

+ V

C '1

+

Kii)

where K

. .

i s the graph i c a l int erc ept inhib i t i o n c onst ant of

l l

I .

3 )

N o ncomp e t i t ive Inh ib it ion

I f the inhib i t o r aff e c t s b o t h t h e s lope and the int er­ c ept of a doub le r e c iprocal p l ot the inh ib i t i o n i s s a id t o

b e nonc omp e titive. T h i s typ e o f inh i b i t ion o c curs whe n t h e

i nhib i t o r a s s o c iat e s with a f o rm o f t h e enzyme wh i ch i s

c onne c t e d by a s e r i e s of reve r s ib l e s t e p s t o t h e form w i th

wh ich t h e variab l e sub strat e comb ines. The e quat i o n at

h ich c onc entrat i o n s of f ixed sub s t rnt e

( B )

is K

1

(

1 '1

1 (

-

I f the i nh ib itor a s s o c iat e s with more than one e nzyme f o r� , or m ore than one in� i b i t o r mol e c u l e b inds t o t h e e nzym e, o r the i nh i b it o r i s such tha t i t forms p art of a n e w re ac t i o n s e qu e nc e , the inh ib it ion p lo t s may b e non­

l inear.

A spe c i a l c l a s s o f i nh ib itor s , the produ c t s of t h e e nzyme r eact ion, are o f part i c u l ar int e rest b e c au s e they provide a m ethod of t e st inG prop o s e d react ion mechanisms. From the propo s e d m e c hanism t h e enzyme f orm w i t h wh ich t h e product s a s s o c i at e i s known and henc e t h e typ e o f inh ib i t i o n H i t h t h e t wo sub s t rat e s may b e predi c ted. If t h e s e pre d i c ­ t ions are n o t veri f i ed exp e r i m ent a l ly , t he me chani sm m ay b e di s carded. C l e l and

( 1 963 )

h a s produ c ed a t ab l e , b a s e d o n t h e inh ib it ion e qu at ions , pre d ict i n� t h e product inhib i t i o n p at t ern s o f a s e r i e s o f me chanisms. Some of t h e s e pat t e rn s a r e shown i n T ab l e 4 . 1 and i l lustrate t h e way in which

p roduct i nhib i t i on p at t e rns may be used to diffe rent iat e m echanisms.

When produ c t inh ib it i o n do e s not g ive unequ ivo c al answers , u s e of inh ib it ors , wh ich reve r s ib ly b i nd t o t h e e nzyme t o form a c omp lex whi c h c annot undergo any furth e r react i o n

(

s o ca l l e d dead-end i nh ib it or s

)

, can E ive furth e r informat i o n about t h e order of sub st rat e b ind inc and t h e e nzyme me ch anism.

56

TABLE 4 . 1

PRO DUCT INHIB IT ION

PATTERNS FOR

B I B I r:JECHAN ISfv1S

In document Problemática del proceso enseñanza aprendizaje de las ciencias naturales en latinoamérica entre 2006 y 2014 (página 62-95)