# What is km in enzyme kinetics?

## What is km in enzyme kinetics?

Km (also known as the Michaelis constant) – the substrate concentration at which the reaction rate is 50% of the Vmax. Km is a measure of the affinity an enzyme has for its substrate, as the lower the value of Km, the more efficient the enzyme is at carrying out its function at a lower substrate concentration.

## Which enzyme does not obey km kinetics?

allosteric enzymes
Unlike many enzymes, allosteric enzymes do not obey Michaelis-Menten kinetics. The reason for this is that allosteric enzymes must account for multiple active sites and multiple subunits. Thus, allosteric enzymes show the sigmodial curve shown above.

What is km equal to kinetics?

The meaning of KM is evident from equation 23. When [S] = KM, then V0 = Vmax/2. Thus, KM is equal to the substrate concentration at which the reaction rate is half its maximal value. KM is an important characteristic of an enzyme-catalyzed reaction and is significant for its biological function.

How do you find KM?

From the graph find the maximum velocity and half it i.e. Vmax/2. Draw a horizontal line from this point till you find the point on the graph that corresponds to it and read off the substrate concentration at that point. This will give the value of Km.

### What is considered a high KM value?

The value of KM is inversely related to the affinity of the enzyme for its substrate. High values of KM correspond to low enzyme affinity for substrate (it takes more substrate to get to Vmax ). Low KM values for an enzyme correspond to high affinity for substrate.

### What is kcat enzyme kinetics?

kcat is the turnover number, the number of times each enzyme site converts substrate to product per unit time. This is expressed in the inverse of the time units of the Y axis. It is the substrate concentration needed to achieve a half-maximum enzyme velocity.

Which enzyme does not follow km constant?

One is that allosteric enzymes do not follow the Michaelis-Menten Kinetics. This is because allosteric enzymes have multiple active sites.

Is Km dependent on enzyme concentration?

Km is the concentration of substrate at which the enzyme will be running at “half speed”. If you doubled the amount of enzyme, sure the Vmax is going to increase. The Km is only related with the enzyme,when the enzyme is given,its Km will not change no matter how or what the condition changes.

## What does km stand for in enzyme kinetics?

Enzymes are often summed up with a graph like this. The bottom represents the concentration of the substrate, the left side represents the initial velocity (we’ll get to that), while the Vmax represents the maximum velocity. That Km? That’s the substrate concentration at which the velocity is ½ of Vmax.

## When does an enzyme achieve maximal catalytic efficiency?

So, if an enzyme has a SMALL KM they it achieves maximal catalytic efficiency (Vmax) at a low substrate concentration! KM is unique for each enzyme/substrate pair KM = substrate concentration [S] when reaction velocity is ½ Vmax if [S] = KM

How are enzyme concentration units independent of substrate?

Independent of substrate or enzyme concentration units are in terms of concentration  Km is a constant derived from rate constants.  KM = k-1 2 + k k1

Which is the maximum rate of enzyme saturated?

Vmax is the maximum rate that can be observed in the reaction substrate is present in excess enzyme can be saturated (zero order reaction) KM is the Michaelis constant

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