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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

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

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

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

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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YouTube 字幕：Enzymes | Biomolecules |Enzyme catalysis | Factors Affecting enzymes catalyze Reactions