In chemistry, the term " turnover number " has two distinct meanings. In enzymology, the turnover number (kcat) is defined as the limiting number of chemical conversions of substrate molecules per second that a single active site will execute for a given enzyme concentration [ET] for enzymes with two or more active sites. [1] .

In enzyme kinetics, we are interested to know how many maximum molecules of substrate can be converted into product per catalytic site of a given concentration of enzyme per unit time. \[ k_{cat} =\dfrac{ V_{max}}{E_t} \] with. The units of Turn over number (kcat) are \(k_{cat}\) = (moles of product/sec)/ (moles of enzyme) or sec-1.

The units of Kcat are time −1. An example would be 35/second. This would mean that each molecule of enzyme is catalyzing the formation of 35 molecules of product every second. While that might seem like a high value, there are enzymes known (carbonic anhydrase, for example) that have Kcat values of 106/second. This astonishing number ...

Kcat/Km就可以用来确定酶的最适底物，同一个酶对不同底物的Kcat/Km最大可相差100万倍。 当利用蛋白质工程对酶进行改造时，不同突变型的Kcat/Km也是需要测定的参数，用来表征酶催化效率的变化情况。

2015年1月5日 · I understand that $k_\text{cat}$ measures the turnover number of an enzyme. This measure is therefore a quantity of molecule conversions per unit of time. I suspect that my problem is more that of a lack of maths but why is the unit expressed in $\mathrm s^{-1}$? Why not just seconds?

The units of kcat are moles of product/sec divided by moles of enzyme. In consequence, kcat resulted in 1/time units. Enzyme concentration can be M, mM, uM, etc.

Notice \(k_2\) describes an irreversible reaction as opposed to an equilibrium expression, when compared to k-1 and k1. k2 here is also known as kcat, the catalytic efficiency of enzyme. From the previous discussion, v0 is the measured reaction rate, which is the product formation over time, so it can be concluded that an equation would look ...

Kcat is turnover number, expresed as number of substrate molecules turned into product per enzyme site per minute. Km and X are both in the same units of substrate concentration. Prism will fit Kcat and Km, each with a confidence interval.

2024年10月1日 · The catalytic constant, kcat, is another crucial parameter in enzyme’s kinetics. It is defined as the number of substrate molecules converted into product by an enzyme per unit time when the enzyme is fully saturated. kcat is often referred to as the “turnover number.”

2015年8月20日 · To get to kcat, you need to divide by the number of nanomoles of enzyme in the reaction. The unit of kcat is 1/s. 3,309,146 nKat x 1 nmol/s/nKat = 3,300,000 nmol/s or 3300 micromole/s. (By...