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Regulation of phenylalanine ammonia-lyase enzyme in Annona fruit: Kinetic characteristics and inhibitory effect of ammonia

AuthorsMaldonado, R.; Goñi Ramos, Óscar ; Escribano, M. Isabel ; Merodio, Carmen
Issue Date2007
PublisherJohn Wiley & Sons
CitationJournal of Food Biochemistry 31: 161- 178 (2007)
AbstractIn this work, we analyzed the kinetic properties of phenylalanine ammonia-lyase (PAL) extracted from >cherimoya> (Annona cherimola Mill.) fruits ripened at ambient temperature (20C) and stored under several environmental conditions, including high CO2 levels (20%) and low temperature (6C). The effect of different ammonia-related compounds on cherimoya PAL activity was also evaluated. PAL exhibited two different Km values for L-phenylalanine (L-Phe) and negative substrate cooperativity, with Hill coefficient (napp) values reaching 0.64 and 0.71 for low temperature and high CO2 levels, respectively. The kinetic analysis revealed that ammonia produced mixed inhibition of PAL enzyme, with inhibition constants (Ki and Ki′ values of 0.57 ± 0.2 mM and 2.54 ± 0.2 mM. We propose that the regulation of PAL by ammonia inhibition and the negative cooperativity may be essential in adjusting the active phenylpropanoid metabolism in Annonas to the requirement of L-Phe and in consequence, to the carbon skeleton demand for other anabolic pathways. © 2007, Blackwell Publishing.
Identifiersdoi: 10.1111/j.1745-4514.2007.00106.x
issn: 0145-8884
Appears in Collections:(IF) Artículos
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