spermine oxidase; polyamine oxidase 1; PAO-1; PAOh1 (SMOX, C20orf16, SMO, UNQ3039/PRO9854)

Function

• amine & polyamine degradation; spermine degradation
• flavoenzyme
• catalyzes oxidation of spermine to spermidine
• can also use N(1)-acetylspermine & spermidine as substrates
• regulation of polyamine intracellular concentration
• determinant of cellular sensitivity to antitumor polyamine analogs (putative)
• beta-alanine production via aldehyde dehydrogenase conversion of 3-amino-propanal
• inhibited at more than 90% by SL-11144, SL-11150 & SL-11158, at concentrations less than 1uM
• low affinity for acetylated polyamine

Cofactor: FAD, noncovalently linked

Kinetic parameters:

• KM=0.6 uM for spermine (isoform 1)
• KM=0.5 uM for spermine (isoform 6)
• KM=3.0 uM for N1-acetylspermine (isoform 1 & isoform 6)
• Kcat is 27-fold higher with spermine than N1-acetylspermine as substrate for isoform 1 & isoform 6
• Optimum pH is 9.5 with spermine as substrate;

Structure

belongs to the flavin monoamine oxidase family

Compartment

cytoplasm, nucleus

Alternative splicing

named isoforms=5

• at least 5 different isozymes are produced by alternative splicing of 8 exons
• the resultant proteins have different biochemical characteristics & substrate specificity

Expression

• widely expressed
• induction by antitumor polyamine analogs

More general terms

• oxidoreductase
• flavoprotein

Database

• Entrez gene: http://www.ncbi.nlm.nih.gov/sites/entrez?db=gene&cmd=Retrieve&dopt=Graphics&list_uids=54498
• Kegg: http://www.genome.jp/dbget-bin/www_bget?hsa:54498
• UniProt: http://www.uniprot.org/uniprot/Q9NWM0.html