homogeneous reaction
TRANSCRIPT
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HOMOGENEOUS
REACTION
MK. Rekayasa Biokimia
Smt. Genap 201!201"
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T#e #ea$t o% a typi&a' (iop$o&ess is
t#e $ea&to$ o$ %e$mente$
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Basi& $ea&tion t#eo$y)
Rea&tion t#e$mo*ynami& how far the
reaction can proceed Rea&tion kineti&s t#e rate o% $ea&tions
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Rea&tion t#e$mo*ynami&s
Re+e$si('e $ea&tion
C'ose* system
thermodynamics equilibrium is$eae*
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Rea&tion t#e$mo*ynami&s
E,-i'i($i-m &onstant K
/A /B /R /S ... e,-i'i($i-m&on&ent$ations
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Rea&tion t#e$mo*ynami&s
T#e +a'-e o% K *epen*s on tempe$at-$e
∆Go$n t#e an3e in stan*a$* %$ee ene$3y
pe$ mo'e
R -ni+e$sa' 3as &onstant
T a(so'-te tempe$at-$e
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Rea&tion t#e$mo*ynami&s
stan*a$* &on*ition 1 atm 4 25oC
t#e$mo*ynami& p$ope$ties
6ot#e$ stan*a$* &on*ition %o$ (ioemi&a'
$ea&tions7
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∆Go$n is e,-a' to t#e *i8e$en&e in stan*a$*%$ee ene$3y o% %o$mation (et9eenp$o*-&ts an* $ea&tants
Rea&tion t#e$mo*ynami&s
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G is $e'ate* to ent#a'py ent$opy an*a(so'-te T
Eot#e$mi& $ea&tion 6 ne3ati+e7 TK
En*ot#e$mi& $ea&tion ne ati+e T
Rea&tion t#e$mo*ynami&s
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:ie'* is t#e amo-nt o% p$o*-&t %o$me* o$a&&-m-'ate*
pe$ amo-nt o% $ea&tant p$o+i*e* o$
&ons-me*
Rea&tion yie'*
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Rea&tion $ate
- T#e $ea&tion $ate &onstant- T#e $ea&tion o$*e$
- E'ementa$y $ea&tion- None'ementa$y $ea&tion
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I$$e+e$si('e $ea&tion)
aA ; bB y : ; z <
RA $ate o% $ea&tion 9it# $espe&t to A
In a &'ose* system)
Rea&tion $ate
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In (iop$o&ess en3inee$in3 t#e$e a$e t#$ee*istin&t 9ays o% ep$essin3 $ea&tion $ate)
Tota' $ate
=o'-met$i& $ate
Rea&tion $ate
6=
&onstant7
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Spe&i>& $ate r A t#e $ate o% &on+e$sion pe$,-antity o% en?yme 6E7 o$ &e''s 6@7 in+o'+e* in t#e$ea&tion
Units o% r A s1 6&e''&ata'yse* $ea&tion7
k3 6-nit en?yme71 s1 6en?yme&ata'yse* $ea&tion7
1 -nit o% en?yme amo-nt o% en?yme 9#i&ata'yses &on+e$sion o% 1 µmo' s-(st$ate pe$
min-te at t#e optima' &on*ition.
Rea&tion $ate
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A'te$nati+e ep$ession %o$ spesi>& $ea&tion$ate)
6+o'-me o% t#e $ea&tion mit-$e
&onstant7
&e'' &on&ent$ation
e en?yme &on&ent$ation
Rea&tion $ate
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T#e $e'ations#ip (et9een $ate o% $ea&tionan* $ea&tant &on&ent$ation an*tempe$at-$e
k $ate &onstant *epen*ent o%tempe$at-$e 6A$$#eni-s7
O$*e$ o% t#e o+e$a'' $ea&tion 6a;(7
Rea&tion kineti&s
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A$$#eni-s e,-ation)
'ot o% t#e 'n k +e$s-s 1!T 3i+es a st$ai3#t'ine 9it# s'ope E!R.
E8e&t o% T on Rea&tion $ate
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E'ementa$y Rea&tion
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T#e Ha'%'i%e
Do$ a >$st o$*e$ $ea&tion t#e #a'%'i%e t1!2 is
&a'&-'ate* as %o''o9s.
Do$ t#e se&on* o$*e$ $ea&tion)
/A at t t /A0
k
693.0t 2/1 =
0
2/1
2/1
o0
]A[k
1 =tor
kt+]A[
1 =
/2]A[
1
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A se-*o>$st O$*e$ Rea&tion Eamp'e #y*$ation o% met#y' io*i*e
CHI6a,7 ; H2O6'7 → CHOH6a,7 ; H;6a,7 ; I6a,7
Rate k /CHI /H2O
Sin&e 9e &a$$y o-t t#e $ea&tion ina,-eo-s so'-tion
/H2O FFFF /CHI ∴ /H2O *oesnt an3e
(y a 'ot
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se-*o>$st O$*e$ 6&ont*7
Sin&e t#e &on&ent$ation o% H2O isessentia''y &onstant
Rate k /CHI /&onstant
k /CHI 9#e$e k k /H2O
T#e $ea&tion is pse-*o >$st o$*e$ sin&e itappea$s to (e >$st o$*e$ (-t it is
a&t-a''y a se&on* o$*e$ p$o&ess.
# *
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T#e Stea*yStateApp$oimation
Eamine t#e %o''o9in3 simp'e $ea&tionmeanism
Rate of product formation, vp,is proportional to the
concentration of an intermediate.
PBA21
1
k k
k →⇔
−
[ ] Bk v Rate p 2==
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#at Is an Inte$me*iateJ
B is an inte$me*iate in t#e a(o+e$e,&tion se,-en&e.
A spe&ies %o$me* in one e'ementa$y stepo% a $ea&tion meanism an* &ons-me*in one o$ mo$e 'ate$ steps.
Inte$me*iates 3ene$a''y sma''
in*ete$minate &on&ent$ations.
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App'yin3 t#e Stea*y State App$oimation6SSA7
ook %o$ t#e inte$me*iate in t#emeanism.
Step 1 B is p$o*-&e*. Re+e$se o% Step 1 B is &ons-me*. Step 2 B is &ons-me*.
[ ][ ] [ ] [ ]Bk Bk Ak
dt
Bd211 −−= −
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T#e SSA 6Cont*7
T#e SSA app'ie* to t#e inte$me*iate B.
[ ]
[ ] [ ] [ ]
[ ] [ ]
21
1
211
k k
Ak B
Bk Bk Ak
0dtBd
+
=
+=∴
=
−
−
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SSA T#e Dina' Step
S-(stit-te t#e ep$ession %o$ t#e&on&ent$ation o% B into t#e $ate 'a9 +p.
[ ][ ]
[ ] [ ]Ak k
k k dtPd
Bk dt
Pd
21
12
2
+=∴
=
−
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SSA Reaction Mechanisms
More examples in sin! t"e stead#$state approximation
on t"e %asis o& t"e &ollo'in! me("anism)
A((ont &or t"e rate la' &or t"e de(omposition o& *2+,
-irst identi t"e intermediates *+ and *+3
2 22,2 g O g NO g O N +→ ][ ,2O N k r =
32,2 NO NOO N ak + →
,232
O N NO NO ak → +
NOO NO NO NO bk
++ → + 2232
2,2 3 NOO N NO ck → +
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1
SSA Reaction Mechanisms
]][[]][[][
,232 O N NOk NO NOk dt
NOd cb −=
]][[]][[][][
3232
,23 NO NOk NO NOk O N k
dt
NOd baa −−=
32,2 NO NOO N ak + →
,232
O N NO NO a
k → +
NOO NO NO NO bk
++ → + 2232
2,2 3 NOO N NO ck → +
]][[]][[][
][,232
,2
,2
O N NOk NO NOk O N k dt
O N d caa −+−=
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SSA - Reaction Mechanisms
A((ordin! to t"e stead#$state approximation set %ot" rates ealto 4ero
0]][[]][[ ,232 =− O N NOk NO NOk cb
][
][
][
][
]][[
2
,23
2
,2
NO
O N
k k
k NO
NO
O N NO
k
k
ba
a
b
c
+==
0][=
dt
NOd 0
][ 3 =dt
NOd
][
bac
ba
k k k
k k NO
+=
][
]][[][
2
,23
NO
O N NO
k
k NO
b
c=
0]][[]][[][ 3232
,2 =−− NO NOk NO NOk O N k baa
][
][
][
][
][
2
,2
2
,2
3
NO
O N
k k
k
NO
O N
k k k
k k
k
k NO
ba
a
bac
ba
b
c
+
=
+
=
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SSA - Reaction Mechanisms
5"e net rate o& ("an!e o& (on(entration o& *2+, is
]][[]][[][][
,232
,2,2 O N NOk NO NOk O N k
dt
O N d caa −+−=
][][
][
][][
][,2
2
,22
,2
,2 O N k k k
k k k
NO
O N
k k
k NOk O N k
dt
O N d
bac
bac
ba
aaa
+−
++−=
][
bac
ba
k k k
k k NO
+=
][
][
][
][
][
2
,2
2
,23 NO
O N
k k
k
NO
O N
k k k
k k
k
k NO
ba
a
bac
ba
b
c
+=
+=
][
][
][,2,2
,2 O N
k k
k k O N
k k
k k k k k k
dt
O N d
ba
ba
ba
aabaaa
+
−
+
+−−=
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SSA - Reaction Mechanisms
%e(ase
6t &ollo's t"at t"e rea(tion rate is
'"ere
][2][
,2,2 O N
k k
k k
dt
O N d
ba
ba
+−=
2][ ,2−=O N υ
][][ ,2,2 O N k O N
k k
k k r
ba
ba =+
=
][ ,2O N k r =
ba
ba
k k
k k k
+=
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SSA - Reaction Mechanisms
1.
2.
.
P C B A ba k k
→ → + ←
ak
]][[][
B Ak dt
P d =