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Process Kinetics Lecture 1 Mahesh Bule 4/27/2017
Template D Plain-white-dark Introduction to Processes in
Biofuel
4/27/2017 Introduction to Processes in Biofuel Heterotrophic and
phototrophic pathway forbiofuel production Template D
Plain-white-dark Important Process and Its Kinetics
Enzymatic hydrolysis Fermentation of soluble sugar Downstream e.g.
extraction, purification etc. Enzyme Kinetics Enzymes are the
agents of saccharification process
What we want to be able to determine: Maximum velocity Substrate
affinity Inhibitor affinity What it can tell us: Utilization of
substrates What can we do with the information: Control and
manipulate process Enzyme Kinetics Basics
Enzyme kinetics studies the reaction rates ofenzyme-catalyzed
reactions and how therates are affected by changes inexperimental
conditions An essential feature of enzyme-catalyzedreactions is
saturation: at increasingconcentrations of substrates the
rateincreases and approaches a limit wherethere is no dependence of
rate onconcentration Consideration of Enzyme Kinetics
Conformation of proteins and positions of side chains areimportant
for enzyme-substrateinteractions and catalysis. Forces involved in
protein folding and structure are also involvedin catalysis-
enzyme-substrate specificity To use enzymes in biotechnology NEED
TO KNOW KINETICPARAMETERS OF THE ENZYME REACTION. We may want
enzymes that WORK FAST- convert more substratein a fixed unit of
time. To do this optimization we have toperform and analyze the
enzyme catalyzed reaction. You can adjust pH, temperature and add
co-factors to optimizeenzyme activity. You cannot adjust substrate
selectivity. Just like chemical reactions, enzyme catalyzed
reactions havekinetics and rates Reaction kinetics is
Michaelis-Menten kinetics. Important things to study
Michaelis-Menten kinetics Interpretations and uses of the
Michaelis- Menten equation Enzyme inhibitors: types and kinetics
Enzyme-substrate cycle Enzyme Kinetics Equation Michaelis-Menten
Equation Initial Velocity (vo) and [S]
The concentration of substrate [S] present will greatly influence
the rate of product formation, termed the velocity (v) of a
reaction.Studying the effects of [S] on the velocity of a reaction
is complicated by the reversibility of enzyme reactions, e.g.
conversion of product back to substrate. To overcome this problem,
the use of initial velocity (vo) measurements are used.At the start
of a reaction, [S] is in large excess of [P], thus the initial
velocity of the reaction will be dependent on substrate
concentration Michaelis-Menten Curve Substrate Saturation of an
Enzyme
A. Low [S]B. 50% [S] or Km C. High, saturating [S] Steady State
Assumption
The M-M equation was derived in part by making several
assumptions.An important one was:the concentration of substrate
must be much greater than the enzyme concentration. In the
situation where [S] >> [E] and at initial velocity rates, it
is assumed that the changes in the concentration of the
intermediate ES complex are very small over time (vo).This
condition is termed a steady-state rate, and is referred to as
steady-state kinetics.Therefore, it follows that the rate of ES
formation will be equal to the rate ES breakdown. Michaelis-Menten
Equation Derivation
Rate of ES formation = k1([ET] - [ES])[S] (where [ET] is total
concentration of enzyme E and k-2 is considered neglible) Rate of
ES breakdown to product = k-1[ES] + k2[ES] Michaelis-Menten
Equation Derivation (cont)
Thus for the steady state assumption: k1([ET] - [ES])[S] = k-1[ES]
+ k2[ES] This equation is the basis for the final Michaelis-Menten
following algebraic rearrangement and substitution of Km and Vmax
terms. [S] V0 = Vmax [S]+Km k-1 + k2 Km= k1 When V0=Vmax, Km=
[S]
Vmax and Km [S] V0 = Vmax [S]+Km k-1 + k2 Km= k1 When V0=Vmax,Km=
[S] Km is unique to each Enzyme and Substrate.It describes
properties of enzyme-substrate interactions Independent of enzyme
conc. Dependent on temp, pH etc. Vmax is maximal velocity POSSIBLE.
It is directly dependent on enzyme conc. It is attained when all of
the enzyme binds the substrate. (Since these are equilibrium
reactions enzymes tend towards Vmax at high substrate conc but Vmax
is never achieved. So it is difficult to measure). When an enzyme
is operating at Vmax, all enzyme is bound to substrate and adding
more substrate will not change rate of reaction (enzyme is
saturated). (adding more enzyme will change the reaction).
Important Conclusions of Michaels - Menten Kinetics
when [S]= KM, the equation reduces to when [S] >> KM, the
equation reduces to when [S]