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This content explains the various factors that influence the rate of enzyme-catalyzed reactions, focusing on how changes in temperature, pH, enzyme and substrate concentrations, product accumulation, activators, coenzymes, inhibitors, and time affect enzyme activity.
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okay um ladies and gentlemen good day
all uh my name is M Ali from Department
of biochemistry a area and you are all
welcome to my YouTube channel and if
this is the first time you coming to my
YouTube Channel please subscribe so in
this video we are going to look at the
numerous factors that affect the enzymes
catalyze reaction so there are the
factors that affect the rat of
reaction and this factors include
substrate concentration enzymes
concentration product inhibition
Inhibitors
so let's start with the temperature so
generally an increase in temperature
increases the increase
the reaction or increase the kinetic
energy of the reacting particles or of the
the
reactants so as you increase the
temperature of the
reactant particles so
generally the kinetic energy of the
molecules of the reactant particles will
increase therefore thetion will be
increased between the reacting particles
let's say in this case you have
a as a
substrate react with
with
D so of course because we are thinking
about enzymes activi so there is an
enzyme cell which is e that converts
this two substrate a and into C and D so
what we are saying here is if you
increase the temperature of the reactant
system if you increase the temperature
of the reactant system the kinetic
energy that is the movement of the the
actom particles will increase it will
increase to elastic collusions so they
will be increase as the temperature
increase the kinetic energy will be
ction between particles and as a result
of that a sufficient amount of energy
will be provided in order for the
reacting particles to convert into the
product so generally the rate of this
reaction increases with an increase the
rate of reaction increase with an
increase in temperature due to increase
in equalution between the parles but of
course as you can see here this is an
optimal temperature Optimum temperature
it means is a temperature that is based
for the enzyme's activity to for the
enzyme's catalysis to occur so this is
the maximum or Optimum temperature and
of course from this optimal temperature
you realize that the rate of the
reaction is that or is decreasing the
rates of the reaction is is
decreasing from here to here so the
reason why the rate of the reaction is
decreasing because generally
enzymes operates at the threedimensional
structure that is in the tertiary andary
structure so as the increase in as the
temperature increases above the opal
temperature the Integrity of the active
side of this enzymes start D
stabilizing so that the substrate itself
cannot be
perfectly fits into the active side due
to the denaturation of the enzymes so
generally as the temperature increases
above the optimal temperature the
enzymes will be the natur and of course
once the enzymes is the nature it means
that the active sides of the enzymes
canot perfectly
bind to
the substance so as a result of that du
to the maturation of the Integrity or of
the threedimensional structure of the
enzymes the activity or the rate of the
reaction will decreases so generally
from let's say from zero as you are
increasing let's say from zero as you
are increasing the temperature as you
are increasing the temperature as you
increasing the temperature of the
reacting system the reaction or the rate
the reaction increases as we can see
here clearly but when the temperature
Optimum that is the optimum temperature
that is the temperature that is
maximally utilized by the enzymes to
conver Subs to product so at it
increases Above This C temperature of
course the protein structure will or the
enzyme structure will tend to be theat
so as a result of that
denaturation the active side of the
enzymes will not
are complementary to the substrate so
therefore the rate of the reaction will
start decreasing of to a zero point
where the enzymes cannot catalyze any
form of
reaction and of course and that is for
the temperature and then the next after
temperature then we have pH pH also we
have optimum pH so generally the rates
of the reaction is increases with an
increase in PH although it depend on the
types of the enzymes there are enzymes that
that
work based at acidic
pH and there are enzymes that work based
at basic
pH so if you have such conditions so
generally as you are increasing the pH
as you are increasing the pH the rate of
the reaction also tend to increase
so as the rate of the reaction increases
with an increase in
PH op pH where enzymes
work best so if higher or lower hydrogen
ion that is in acids or o in alkaline
base can in spere can interfere enzyme
structure so it depend on the
concentration of the so is depend on the
ph and the types of the enzym some
enzymes work based at acidic pH while
some enzymes work based at an alkaline
pH that is above s point and some below
zero and some of course work at a
neutral pH so generally an increase in
pH for example if it is
uh alkaline if it is alkaline of course
the pH of an alkaly is generally about
seven so when the pH of an alkaline
medium where the enzymes work start
decreasing it means that it will be
changing from an alkaline environment
going back to the acidic environment so
as a result of that the
pH can interfere with the enzyme
structure and of course if it is if if
the enzymes work at an at an acidic pH
and it now increases
from acidic to
phasic so it means that the structure of
the enzy should also be aced so as a
result of that the activity of the
enzymes will be decreased
so that's what happened so as the pH
increases as the pH increases or
decreases that leads to interfere with
the enzyme structure and it affects the
activity of the enzymes so but generally
as you increase the pH the activity of
the enzymes increase up to it is optimum
pH but
as the optimum pH
is random that or is surender whether by
decreasing or
increasing which leads to interference
of the enzy structure then the activity
will decrease and then the next thing is
enzymes concentration so as you increase
the concentration that is the amount of
the enzymes you are also increasing the
rate of the reaction so generally an
increase in enzymes concentration leads
to increase in the rate of the reaction
because as you are increasing the
concentration of the enzymes it means
that you it means that at the same time
you increasing the amount of The Binding
sites for the substrate that is the
amount of the active sites are also
increasing so that more of the substrate
can be bed and converted to product so
we have a steady state if a substrat
available so
generally generally as if you can now
see this from here to here it tells us
that as you increase the concentration
of the enzymes and of course the rate of
the reaction will increase so that
because there are more active side of
the enzymes that are available for
binding with the
substrat but if the substrate is limited
that when it means when say the
substrate is limited that means that
it's a situation where you have more of
the active SES then the substrates and
all the substrate are now bind to the
active SES for the
catalysis and no more other three
substrate and of course the rate of
theaction will start declining it will
start declining so it means that for the
reactions to proceed simultaneously
without supp to increase continuously it
means that both the concentration of the
enzymes on the substrate must be
increased at the same time and then the
next thing is substrate concentration so
substrate concentration also increase
rate of di action so it means that the
reaction the more the substrate will
balance to the active side of the
enzymes and of course the rate of the
reaction that the speed of the reaction
will also
increase but if you now reach to a
point where all the enzymes or all the
active side of the enzymes are used
of the some substra remain three that
there is no available active SES BS so
it means that it will now reach to a
saturation state that is where we have
this parabolic
shap graph so you see here as you
increase the subate concentration the
rate of theaction increases but if all
the active side of the enzymes available
is being saturated with the substrates
so what will happen to narate a platin
where there is no increase or decrease
of the action but at the starting point it
it
increases but when it reach this it
means that all the active side of the
enzymes is being filled off with the
substrate that is where we have
maximum velocity this is where we have
maximum velocity that is V Max it means
that the enzymes reach it is V
Max so that is actually for
the for this part with these four
factors temperature increases the rate
of the reaction but further increase
will Le to the nature of the enzymes and
also uh enzymes have optimum pH
depending on the types of the enzymes
and the
medium that the enzymes require so if an
increase or change in the pH alter will
interfere with the en structure and of
course the activity of the enzymes will
be decreased and of course generally an
increase in PH leads to increase
in enzymes reaction which is thereby
increasing the rate of the reaction
reaction
so this is
for enzyme for the four factors that are
affecting the rate of the reaction so
now the next thing that we are going to
look at is of course the effect of the
substrate concentration as you said so
the Shi of the C that relate activity to
substrate concentration is hyperbolic so
this is hyperbolic shell and of course
this is the first order reaction this is
the F order reaction it means that an
increase in the substrates have effects
on the increase in the concentration so
have effects on the increase in the rate
of dition so we have f order so from
here to here from here to here we have
first order it means that an increase in
the rate of the reaction is depend on
the increase in the concentration of the
substrate that is the reactant and of
course this is a zero order reaction you
said zero order reaction it means that
at this point the rate of the reaction
doesn't have any effect it doesn't have
any effect on on the rate of the
reaction because all the substrate is
been is occupied who have occupied the
active side of the enzyme so that is why
it's zero order so the r of the reaction
is independent on the concentration of the
so so like for example here if you can
look at at point A and B this is point a
this is our point
a and this is our Point P so if you can
see point A to B there's an increase or
decreasing substrat there is an
increasing or decreasing concentration
of the subsrate
thereby will increase or decrease the
number of enzyme substrate complex with
a corresponding change in velocity that
initial velocity so the rate of the
reaction is subrate dependent which is
first over reaction then at Point C at Point
Point
C essentially all the enzymes is present
at the enzyme substrate complex
stage means that the the enzymes and
being formed together and there is no
any free enzymes no any free enzymes so
it means that all the enzymes at Point C
is present at enzyme subrate complex
since no free enzymes remains available
for forming enzy substrate complex the
further increase in substrate
concentration cannot increase the rate
of the reaction so reaction rate
therefore becomes independent of
substrate concentration and that is zero reaction
reaction
so the zero order reaction it's point
enzymes is completely filled with the
substrate and increasing the
concentration of the substrate doesn't
so so we have km and it is significant
so my constant which is KM my cening
constant km is the is the substrate at
which the initial velocity half or is
half the maximum velocity of course we
know that as I
said when the enzymes is completely
filled with the substrates and at that
point you have all the enzymes at a
stage of enzyme substrate complex so at
that stage it means that you have V Max
we have V
Max that stage we have B
maass so as I was seeing it means that
the when you have
enzymes and you have
enzymes you have enzymes subrate complex
mean means that there is no free enzymes
at this stch it means no means no free
enzymes no free enzym so all the enzymes
at this stage is being utilized for the
formation of En substrate complex
therefore it means that the enzymes is
at is at it is V Max it is at it is
maximum velocity and of course there's a
relationship between km and Vmax there's
a relationship between km and Vmax and
the relationship is that km is equal to
half V Max so km is half b
max so it means that when you have your
enzymes starting from here then it now reach
reach
to this platin Stitch where all the enzymes
enzymes
and the substrate form enzyme substrate
complex so no free enzymes so it means
that the rate of the
reaction reach it is V Max that is it is maximum
maximum
velocity and the relationship between km
and V Max is half Max so T the km has
the dimension of substrate concentration
so it is specific and constant so this
km specific and it is constant for a
given enzymes under defin conditions of
time temperature and pH so there are
enzymes because we have different
enzymes we can have glinus and
hexus they are although they are
isozymes they are enzyme that catalyze
the same substrates but they have different
different km
km
under fine conditions of time
temperature and pH H so even within
isozymes you can have isozymes with
different values and of course the
enzymes that catalyze different types of
theaction have different km value and
this km values determine the Affinity of
enzymes for its substrate and the laser
the km for the
affinity for yeah so it means that what
this means is that the k is used to
determine the Affinity of the enzymes
toward it is substrate and the lower the
km the lower the km the higher the
Affinity of the enzymes it means that if
you now have enzymes a and enzymes [Music]
[Music]
B enzymes a and enzymes B and enzymes a
have low
km while enzymes B have
higher km so what does that means it
means that the enzymes with lower km
have Affinity or have the ability to
bind the substrate more more than the
one with the higher km value so km value
it helps in determining the true
substrate for the enzymes so you can use
this km value to
determine the best substrate for a particular
particular
enzymes so that is for the km value and
it is significant so you can use it in
Discovery by knowing the key for a
particular Inhibitors it will give us an
idea whether the drugs will be the
goods or the targets of a particular
Interest so now the next the the the
next factors that affect the rate of
reaction is the effect is the effect of product
product
concentration so generally in a
particular partway in a given partway in
a given
partway like for
example uh the products of a particular
of the starting
enzymes of that particular part like for
example this is a
pathway the first enzyme is enzymes one
so we have enzymes 2 enzymes three and
we have the
product so but in this case the product
of this reaction now
inhibites the face enzymes of that
reaction and the process of this is
called feedback inhibition like for
example generally like in glycolysis we
have what you call glycolysis so in
glycolysis we have
glucose and the glucose is converted
through a series of like about 10
reactions a phyit is generated your f f
bits is generated
and of course the F the first enzymes
for glycolysis is hexo Kus so if the
fire which is the end product of
glycolysis is
accumulated or is produced in high
amount so this products will now go back
and inhibit the face enzymes of this
pathway that is the face enzymes of
glycolysis so this type of inhibition is
called feedback it's called feedback
inhibition so when the enzymes of a
particular pathway is inhibited by the
product or by the final product of that
pathway so the process of this
inhibition is called feedback inhibition
so under certain conditions the reverse
reaction may be favored foring back the
substrate so that is why whenever you
have this kind of inhib that is feedback
inhibition like in glycolysis so it
means that the back reaction that is the
r reaction will be favored that is
whenever you have feedback inhibition in
glycolysis so it means that there will
be glucogenesis
gluc neo
genesis so we said gluc neogenesis it
means gluco means glucose gluco means
glucose and then Neo means means new
means new and Genesis of course is
synthesis is
synthis so it means that in the feedback
inhibition here glucose produce fyro and
the fet is accumulated and it now
inhibit the enzyme so it means that the
substrate here which is pyro will now go
back and synthesize glucose so the
process of doing that is called
gluconeogenesis and that is a typical
inhibition so the next time is the
effect of activators and coenzymes so
the activity of certain enzymes is
greatly dependent on metal uh activators
and coenzymes so vitamins most of the
vitamins they act as coenzymes in a
variety of reactions so like for example
from the previous um from the
previous we talk about
glycolysis so like for example in this
glycolysis the first reaction in
glycolysis is the conversion of glucose to
glucose six phosphates glucose six
phosphates and of course in this
reaction enzymes called hexin is repair
and ATP ATP is
utilized and glucose 6 phosphate and
ATP are generated are generated but this
enzy exocin require a
coraor requ a metal ions it requires a
metal ions magnesium ion magnesium
2+ so this is an example of co-actors
that is
require to make this exocin active for
it to conver glucose glucoses posate the
process of doing this is the effect of
activators and the core enzymes and of
reactions and of course these types of
reaction is the types of reaction that
have effect on both the activators and
the co enzymes and uh for that
we can have some reaction that require
Co enzymes like for example we have an
enzym called glycer three phosphate
dehydrogen in glycolysis it require Co
enzyme and the co enzyme is n e n plus
n nucleo
Nite nucleo so this is the examples of
the co enzymes that is require for these
types of reaction so they are very
essential they affect the they are
factors that affect the rate of the
reaction and if there is no this Co
factors and coenzymes the reaction may
occur so now the next thing is the
effect of modulators and Inhibitors so
enzymes activity is generally reduced in
the France of an
inhibitor and when you said Inhibitors
it means that there are the molecules
that usually bind to the enzymes and the
bend would increase the activity of the
enzymes so generally
as there is an increase if there is an
increase in inhibitor there will be
decreasing enzy activity and there's
also modifier that is positive modifiers
which are call activators so what they
do what they do they increase the rate
of the reaction they increase the rate
of the reaction so Inhibitors and activ
so positive moders positive
modifier activators so they generally
increase the rate of theaction and then
the next thing is effect of time so the
longer an enzyme is incubated with it is
substrate the greater the amount of the
product that will be formed however rate
of formation of product is not a simple
linear functions of a time of incubation
so o protein Su nitration and H loss of
catalytic activities with time
so time is important but the incubation
time is important because there are some
points that when you allow your reacting
system to stay
long maybe with an increase in
temperature that is likelihood that the
proteins will suffer the ntion and once
that happen it means that there will be no
no
activity this is an example of enzymes
catalyzed reaction on the completion in
an Optimum time so you look at it as an
Optimum time so if you can now clearly
see this you can see that with the time
with the time it's time with an increase
in time there is an increase in product
formation but you see at this point it
start going down so that is it means
that if you now allow it to continue
like this then it will affect the
reaction so variations of time affect
the rates of enzymes catalyze reactions
so ladies and Gent
this is the end of The Today class which
is the factors that affects the rate of
the chemical reaction and if this is the
first time you are coming to my YouTube
Channel Please Subscribe for more video
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