High impact information on HEM3

• A hem3 mutant was isolated which was also blocked between 2,3-oxidosqualene and lanosterol (erg12) [1].
• Analysis of the plasmid designated YEpPBG-D (containing the PBG-D gene) by hybrid-selected translation revealed that it contained the coding information for a single protein of apparent Mr 43,000 [2].
• The complementing gene restored growth of the hem 3 (PBG-D) mutant strain on media in the absence of exogeneous haem or fatty acid and sterol supplements [2].
• These findings suggest that HEM3 expression is regulated in the same manner as that of HEM1 which encodes the first enzyme of the heme biosynthetic pathway [3].
• However, we have found that HAP2 and HAP3 gene products are involved in the expression of HEM3 [3].

Biological context of HEM3

• An important element required for expression of HEM3 has been localized to a small region that contains a sequence homologous to the HAP2-3-4 binding sites of several genes including HEM1 [3].
• Porphobilinogen-deaminase exhibited classical Michaelis-Menten kinetics [4].

Anatomical context of HEM3

• Neither LPS nor zymosan increased ROS production by granulocytes incubated in PBG media [5].

Associations of HEM3 with chemical compounds

• Earlier reports have suggested that expression of HEM3 is induced by porphobilinogen, the substrate of the encoded enzyme [3].
• Porphobilinogen-deaminase from Saccharomyces cerevisiae has been isolated and partially purified 80- and 230-fold in the absence or presence of phenylmethylsulphonyl fluoride, respectively [4].
• When the enzyme, partially purified in the absence or presence of phenylmethylsulfonyl fluoride (PMSF) and preincubated with PBG, was applied on DEAE-cellulose columns, three peaks with PBG deaminase activity were detected [6].
• 1. Different porphobilinogen-deaminase (PBG-D) enzyme forms were found for D 27 and D 27/C6 (HEM R+) strains of Saccharomyces cerevisiae [7].
• The enzyme porphobilinogen deaminase (PBG deaminase, EC 4.3.1.8) catalyzes the condensation of four molecules of PBG to give the linear tetrapyrrol, hydroxymethylbilane [6].

Analytical, diagnostic and therapeutic context of HEM3

• Peroxidase activity increased significantly after repeated oral administration of CMG and PBG at doses 150 and 50 mg/kg, SEG 150 mg/kg body mass [8].

References