Formation of aromatic intermediates in the biosynthesis of bitter acids in Humulus lupulus

Zuurbier, Karin W.M.; Fung, Suen‐Ying; Scheffer, J. J. C.; Verpoorte, Robert

doi:10.1016/0031-9422(94)00614-y

Cited by 44 publications

(35 citation statements)

References 14 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Their major contribution to beer is the characteristic bitterness that results from isomerization of the hop bitter acids. The biosynthetic pathway of α and β bitter acids was analyzed by Zuurbier et al (1995). A condensation reaction catalyzed by a chalcone synthase-like enzyme was proposed for this pathway.…”

Section: Introductionmentioning

confidence: 99%

Chalcone synthase homologues from Humulus lupulus: some enzymatic properties and expression

Novák¹,

Krofta²,

Matoušek³

2006

Biol. plant.

View full text Add to dashboard Cite

The enzymatic properties of four chalcone synthase homologues CHS_H1, VPS, CHS 2 and CHS 4 from Humulus lupulus L. were investigated after heterologous expression in Escherichia coli. It was found that both VPS and CHS_H1 can utilize isovaleryl-CoA and isobutyryl-CoA as substrates producing compounds with positions in thin layer chromatography characteristic for phloroisovalerophenone and phloroisobutyrophenone. These reactions are accompanied by the formation of associated byproducts. The formation of naringenin chalcone can be catalyzed primarily by CHS_H1. Comparatively the ability of VPS to perform chalcone synthase reaction is very limited. Since only CHS_H1 has true chalcone synthase activity, this enzyme can be considered a key enzyme in prenylflavonoid biosynthesis. Both CHS 2 and CHS 4 utilize isovaleryl-CoA and isobutyryl-CoA as substrates, but the reactions were prematurely terminated. In comparison with VPS and CHS_H1, the optimum pH of CHS 2 was shifted to lower value. High expression of chalcone synthase-like genes were found in maturating hop cones of cultivars with high bitter acid content (Agnus, Magnum, Target) by Northern and Western blotting using probes specific for vps, chs_H1, chs 4 and polyspecific serum risen against recombinant protein CHS4, respectively. It was also found that these cultivars maintained expression of CHS homologues for a longer period of time during cone development in contrast to timelimited expression of CHS homologues in cultivars with low bitter acids content.

show abstract

Section: Introductionmentioning

confidence: 99%

Chalcone synthase homologues from Humulus lupulus: some enzymatic properties and expression

Novák¹,

Krofta²,

Matoušek³

2006

Biol. plant.

View full text Add to dashboard Cite

show abstract

“…In previous papers [5,6] a novel biosynthetic pathway leading to the bitter acids in H. lupulus was proposed. The suggested intermediates phlorisovalerophenone and phlorisobutyrophenone were also detected in hop cones.…”

mentioning

confidence: 99%

“…Chalcone synthase protein and its enzymatic activity were also detected in protein extracts from hop [5]. However, the profile of phlorisovalerophenone and phlorisobutyrophenone formation during cone development was different from that of naringenin formation.…”

mentioning

confidence: 99%

Phlorisovalerophenone synthase, a novel polyketide synthase from hop (Humulus lupulus L.) cones

Paniego

Zuurbier

Fung

et al. 1999

European Journal of Biochemistry

Self Cite

View full text Add to dashboard Cite

Phlorisovalerophenone synthase (VPS), a novel aromatic polyketide synthase, was purified to homogeneity from 4.2 mg protein extract obtained from hop (Humulus lupulus L.) cone glandular hairs. The enzyme uses isovaleryl-CoA or isobutyryl-CoA and three molecules of malonyl-CoA to form phlorisovalerophenone or phlorisobutyrophenone, intermediates in the biosynthesis of the hop bitter acids (a-and b-acids). VPS is an homodimeric enzyme, with subunits of 45 kDa. The pI of the enzyme was 6.1. K m values of 4 mm for isovaleryl-CoA, 10 mm for isobutyryl-CoA and 33 mm for malonyl-CoA, were found. The amino-acid sequences of two peptides, obtained by digestion of VPS, showed that the enzyme is highly homologous to plant chalcone synthases. The functional and structural relationship between VPS and other aromatic polyketide synthases is discussed.Keywords: Humulus lupulus; chalcone synthase; polyketide synthase; hop bitter acids; phlorisovalerophenone synthase.The cones of the hop plant (Humulus lupulus L.) have been used for centuries in the beer-brewing process. Their major contribution to beer is the characteristic bitterness that results from the isomerization of the hop a-acids into a more soluble and stable form during the brewing process; isomerized a-acids are the main bitter substances in beer. In the plant, hop bitter acids consist of both a-acids, mainly humulone, cohumulone and adhumulone, and b-acids, mainly lupulone, colupulone and adlupulone [1]. These compounds are synthesized during the development of the H. lupulus female inflorescences into cones and are accumulated in the yellow glands covering the basal part of the bracteoles of the cones [2,3]. In general, glands are a rich source of secondary metabolites. Recently, strategies for bioengineering the development and metabolism in glandular tissues have been reviewed [4].In previous papers [5,6] a novel biosynthetic pathway leading to the bitter acids in H. lupulus was proposed. The suggested intermediates phlorisovalerophenone and phlorisobutyrophenone were also detected in hop cones. Furthermore, protein extracts from the cones were able to synthesize these compounds from malonyl-CoA plus either isovaleryl-CoA or isobutyryl-CoA. Apparently, the catalytic mechanism involved in this biosynthesis is similar to that observed in other plant condensing enzymes, like chalcone synthase and stilbene synthase (Fig. 1). These enzymes catalyze a reaction which proceeds by a sequential condensation of three acetate units to a starter residue to form the tetraketide intermediate that is folded to form a ring [7,8]. This type of reaction, which was first described by Birch and Donovan [9], classifies chalcone synthase and stilbene synthase as polyketide synthases. Chalcone synthase is a key enzyme in the biosynthesis of flavonoids. It catalyzes the formation of naringenin from three molecules of malonyl-CoA and coumaroyl-CoA. Stilbene synthase, an enzyme in the biosynthesis of stilbene phytoalexins, is structurally and functionally related to chalcone synthase. Usi...

show abstract

“…The intermediate polyketide 10 can then cyclize via an intramolecular Dieckmann condensation to produce acylphloroglucinol 11 [31,32]. Subsequent prenylations (or geranylations) occur via an enzymatic process that involves prenyltransferase-catalyzed reactions of the appropriate diphosphates with phloroglucinol [25,[33][34][35][36][37]. This stepwise prenylation process is illustrated in Scheme 12.1 for the construction of 12 and 13 (deoxycohumulone) from 11.…”

Section: Introduction and Chemical Classificationmentioning

confidence: 99%

Polyprenylated Phloroglucinols and Xanthones

Theodorakis

2011

Biomimetic Organic Synthesis

View full text Add to dashboard Cite

Formation of aromatic intermediates in the biosynthesis of bitter acids in Humulus lupulus

Cited by 44 publications

References 14 publications

Chalcone synthase homologues from Humulus lupulus: some enzymatic properties and expression

Chalcone synthase homologues from Humulus lupulus: some enzymatic properties and expression

Phlorisovalerophenone synthase, a novel polyketide synthase from hop (Humulus lupulus L.) cones

Polyprenylated Phloroglucinols and Xanthones

Contact Info

Product

Resources

About