Human Immunodeficiency Virus-1 Protease
Introduction
HIV -1 protease (HIV PR ) is a retroviral aspartyl protein that is derived from HIV-1, a lentivirus that is best characterized for its ability to lower host immunity by infecting CD4+ T lymphocytes, macrophages, and dendritic cells. Unlike most members of aspartyl protease class, which generally exist as two domain monomers, HIV protease is a dimmer with two identical subunits that are comprised of 99 amino acids. The HIV PR, together with single stranded RNA (ssRNA), reverse transcriptase, integrase, and other viral factors, is found inside the HIV-1 virion. As an important viral protein, it plays a crucial role in successful viral propagation.
Structure & Function
Mechanism
Applications & Research
When a HIV virus infects an organism it tends to multiply within the body’s cells. The virus is then released to infect other cells. In this manner, the infection of HIV infects the newly made cells of the body. While the viruses are produced, proteins and enzymes used to manufacture the DNA in addition to other components of the virus are made. In this case, protease is that enzyme that is needed to bring the structural and enzymes of the virus together. Protease drugs are what could inhibit this virus.
HIV Drugs:
1) Saquinavir (Invirase) is known to be one of the first FDA approved protease inhibitor for HIV treatment. This usually occurs by HIV protease binding an active site tunnel tightly, which will prevent polyproteins from also binding. HIV’s chemical structure has the ability to mimic the tetrahedral intermediate of the hydrolytic reaction to interact strong with the catalytic Asp residues. Knowing that, Saquinavir is an uncleavable ligand by studying its similar conformational changes in binding saquinavir or a polypeptide. (((http://ispcsrv3.weizmann.ac.il/wiki/index.php/Hiv_protease))))
2) Indinavir (Crixivan) this protease inhibitor is an oral medication that blocks the protease activity and leads to defect the viruses. Once these viruses are unable to reach the body’s cells, it will decrease in number. This inhibitor doesn’t have the ability to prevent the HIV transmission among individuals, nor does it cure AIDS or HIV infection. Indinavir is approved by the FDA in March 1995. ((((http://www.medicinenet.com/indinavir/article.htm )))
3) Ritonavir (Norvir), has the same effect of indinavir on HIV protease. It was approved by the FDA in June 1999. This drug consists of capsules or tablets 100 mg; Solution: 80 mg/ml. It is recommended that adults consume 600 mg twice a day and then increase by 100 mg in every 2 days. Ritonavir can interact with many drugs leading those drugs to increase or decrease in effectiveness. It increases the concentration of Mycobutin and Viagra; however, decrease the concentration of Demerol. ((((http://www.medicinenet.com/ritonavir/article.htm))))
4) Nelfinavir (Viracept), Nelfinavir was approved by the FDA in March, 1997. Nelfinavir has not been effectively evaluated in pregnant women. Viracept prevents T-cells that have been infected with HIV from producing new HIV. Usually given to patients through tablets. Each tablet contains inactive ingredients such as: calcium silicate, magnesium stearate, hypromellose, and triacetin. ( Picture ) http://www.rxlist.com/viracept-drug.htm
((http://www.ncbi.nlm.nih.gov/pubmedhealth/PMH0001007/))
APPLICATIONS:
Design of a HIV-1 Protease inhibitor - Free-energy parameterization of enzyme-inhibitor binding.
Based on the crystal structure data and protein receptor ligand complexes studied, interatomic interactions that work on burying atoms and find the statistical preference for amino acid pairs. A free energy model of the receptor-ligand is formulated and helps in showing the interfacial interactions. The interaction strength of this model has a reliability of ±1.5 kcal/mol, which reveals the importance of atomic interaction to stabilize the receptor-ligand interface. The analysis of a binding motif of HIV-1 protease inhibitor complex shows the important contacts instead of the set of atoms.
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