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Molecule Parameter List for Hemeoxyg2

The statistics table lists the distribution of a molecule acting either as a substrate, product, enzyme or as a molecule within the network.
The text color of a molecule is highlighted by color.
Statistics
Hemeoxyg2 participated asMoleculeSum total ofEnzymeSubstrate of an enzymeProduct of an enzymeSubstrate in ReactionProduct in Reaction
No. of occurrences1010000

Accession and Pathway Details
Accession NameAccession No.Accession TypePathway Link
  • CO_activation_
    of_GC
  • 28Pathway
    sGC 
    Carbon Monoxide is an activator of soluble Guanylyl Cyclase and has been implicated as a neuronal messenger [Ingi T. et al. Neuron (1996) 16(4):835-42].
    CO binds to the heme group on sGC, similar to NO binding. Exogenous CO at similar conc. to endogenous levels were used to study the extent of activation of GC. Olfactory receptor neurons were used by Ingi et al., to investigate the relationship of CO to cGMP levels, as these cells have high levels of HO activity but no NOS activity.
    Kharitonov VG. et al. Proc Natl Acad Sci U S A. (1995) 92(7):2568-71 and
    Kharitonov VG. et al. Biochemistry (1999) 38(33):10699-706 report the presence of a six coordinate and a five coordinate intermediate of carboxy GC, induced by CO. Considering that activation of sGC by CO is similar in almost all tissues, some rates have been taken from original published works cited as references in Kharitonov et al., and Ingi et al., the primary datasources, this model is based on.

    Hemeoxyg2 acting as a Molecule in  
    CO_activation_of_GC Network
    NameAccession NamePathway NameInitial Conc.
    (uM)
    Volume
    (fL)
    Buffered
    Hemeoxyg2
  • CO_activation_
    of_GC

    Accession No. : 28
  • sGC
    Pathway No. : 140
    20.0016667No
    Heme oxygenase 2 (HO-2)-Highly expressed in Brain (Sun et al., 1990, J Biol. Chem., 265: 8212-8217), with discrete neuronal localization demonstrated throughout the brain with in situ hybridisation and immunohistochemical studies (Verma et al., 1993, Science, 259: 381-384). Mol. Wt. of HO-2 is 36 kDa.(Migita et al., JBC,1998,273(2):945-949.) Three mammalian isoforms have been identified. HO-1, is inducible and highly concentrated in tissues and involved in catabolism of heme proteins. HO-3, is an isoform with low catalytic activity, with uncertain physiological role. (Montellano, PRO., 2000, Curr Opin in Chem Biol, 4:221-227)

    Hemeoxyg2 acting as an Enzyme in  
    CO_activation_of_GC Network
    Enzyme Molecule /
    Enzyme Activity
    Accession NamePathway NameKm (uM)kcat (s^-1)RatioEnzyme TypeReagents
    Hemeoxyg2 /
    HOXY
  • CO_activation_
    of_GC

    Accession No. : 28
  • sGC
    Pathway No. : 140
    3.800040.35564explicit E-S complexSubstrate
    Heme

    Product
    CO
    Ingi et al., J Neurosci., 1996, 16(18):5621-5628, report the production rates of heme precursors and metabolites. The rate reported for CO from heme is 2.9 pmol/mg protein over 6 hr. Their results indicate high HO activity in brain (along with significant levels of heme) at around 280pmol of bilirubin/mg/min. Montellano PRO, Curr. Opin. in Chem. Biol, 2000,4:221-227 and refs cited in his paper were also studied initially. Km for free heme is around 3.8 +/- 0.5 uM.(Bonkovsky et al., 1990, 189(1):155-166)



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