Rapid Minoxidil Response Test

Rapid  Minoxidil Response Test is a biochemical assay based on  plucked hair follicle sulfation reaction

Principle:

The plucked hair follicle sulfation reaction involves the transfer of a sulfonyl group (SO3-) from a donor molecule, 3′-phosphoadenosine-5′-phosphosulfate (PAPS), to an acceptor molecule, p-nitrophenol (PNP), catalyzed by the enzyme sulfotransferase. This reaction can be represented as follows:

                 PAPS + PNP → PAP + p-nitrophenylsulfate (PNPS)

The sulfonyl group is a highly reactive group that can be transferred to a variety of acceptor molecules, including phenolic compounds like PNP. The reaction is driven by the hydrolysis of the high-energy phosphate bond in PAPS, which releases energy that is used to overcome the activation barrier for the sulfonyl group transfer.

The enzyme sulfotransferase plays a crucial role in facilitating the sulfation reaction by bringing the donor and acceptor molecules together and aligning their binding sites. The enzyme has two distinct binding sites: one for PAPS and one for the acceptor molecule. When PAPS and PNP bind to their respective sites, the enzyme undergoes a conformational change that brings the sulfonyl group of PAPS into close proximity to the hydroxyl group of PNP. This alignment facilitates the nucleophilic attack of the hydroxyl group on the sulfonyl group, leading to the formation of PNPS and the release of PAP.

1. Binding: PAPS and PNP bind to their respective binding sites on the enzyme.

2. Conformational Change: The enzyme undergoes a conformational change, bringing the sulfonyl group of PAPS and the hydroxyl group of PNP into close proximity.

 3. Nucleophilic Attack: The hydroxyl group of PNP attacks the sulfonyl group of PAPS, forming a covalent bond and releasing pyrophosphate.

 4. Product Release: The enzyme releases PNPS and regenerates its active form, ready for another catalytic cycle.