km value and Vmax - (Jul/18/2006 )

hi
i am sorry to ask u about this....
can anyone please explain me what is km value and Vmax. i tried to understand by reading some biochemistry books but i cannot understand by myself

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Vmax is the maximal speed of activity of the enzyme, i.e. what is the fastest it can convert substrate to product. This is measured as the rate at infinite substrate concentration. Units depend on how you measure your rates but generally something like M.s^-1

Km is the concentration of substrate required to produce 50% of the Vmax value. It is measured in units of concentration (generally M).

Competitive and non-competitive inhibitors produce different changes to Vmax and Km values.

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For simple: An enzyme velocity is dependent of the substrate concentration. The velocity increase up to an maximal velocity, where the enzyme works on its maximum. Km is the substrate concentration, where the enzyme works with half maximal velocity. The KM is, simple spoken, a dimension for the enzyme affinity to its substrat.

But for a very good and easy explaining look here!

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