which is duplicated. One clone from Acremonium coenophialum hybridizes with
DNA from Claviceps purpurea, making it a good candidate for involvement in
ergopeptine production. The authors concluded that ergopeptine-producing
fungi have multiple families of peptide synthetase genes.
A comparative analysis of the nucleotide sequences of the structural gene for
farnesylpyrophosphate synthase (FPPS), a key enzyme in the isoprenoid biosynthesis, of Neurospora crassa, Gibberella fujikuroi, Sphaceloma manihoticola,
and Claviceps purpurea showed the presence of conserved regions [76].
In parallel, recent studies on enzymology of Claviceps purpurea have given
us an insight to the molecular mechanisms and the information will be of importance to molecular biologists. The elucidation of the mechanism of reaction
of dimethylallyltryptophan synthase [77] is worth mentioning. The authors
showed that the prenyl-transfer reaction catalyzed by DMAT-synthase is an
electrophilic aromatic substitution and is mechanistically similar to the
electrophilic alkylation catalyzed by farnesyldiphosphate synthase. The other
significant work was the purification of an enzyme activity capable of synthesis
of d-lysergyl-l-alanyl-l-phenylalanyl-l-proline lactam, the noncyclol precursor of ergotamine [78]. Amino acid activation and lysergic acid activation
domains were identified. Kinetic analysis indicated that under in vivo conditions, d-lysergyl peptide formation is limited by the d-lysergic acid concentration of the cell. The enzyme was also found to be produced constitutively.
Studies on substrate specificities of this enzyme, d-lysergyl peptide synthetase
(LPS), by the same research group showed that the peptide synthetase domain
catalyzing the incorporation of proline appears to be specific for this amino
acid [79].
4
Fermentation Technology
The review [2] describes the large-scale production of ergot alkaloids in bioreactors. It contains information of media, operating conditions, and purification processes. Another review [3] extensively describes the fermentative production of the alkaloids including the basis of the selection of carbon and
nitrogen sources, the addition of trace elements, antifoam agents, the temperature of cultivation, and aeration requirements. This review also mentions
semicontinuous fermentation, scaling up, culture rheology, bioreactor design,
and solid state fermentation. The production of ergot alkaloids covering the
selection of the carbon and nitrogen sources and environmental factors
affecting the fermentative production has also been described [6]. Another
recent review [8] covers the large-scale production of ergot alkaloids.
The effect of some stimulants and depressants of alkaloid production, the use
of oxygen vectors, recent studies on solid state fermentation, and mathematical
modeling, which have not been reviewed earlier, are covered in this section.
The oxidation and cyclization of chanoclavine is dependent on the cultivation conditions. The enzyme, chanoclavine cyclase, reponsible for this biochemical reaction, is a membrane bound enzyme and is thus influenced by
membrane-affecting agents. This was studied with Claviceps purpurea mutant
Progress and Prospects of Ergot Alkaloid Research
13
DNA from Claviceps purpurea, making it a good candidate for involvement in
ergopeptine production. The authors concluded that ergopeptine-producing
fungi have multiple families of peptide synthetase genes.
A comparative analysis of the nucleotide sequences of the structural gene for
farnesylpyrophosphate synthase (FPPS), a key enzyme in the isoprenoid biosynthesis, of Neurospora crassa, Gibberella fujikuroi, Sphaceloma manihoticola,
and Claviceps purpurea showed the presence of conserved regions [76].
In parallel, recent studies on enzymology of Claviceps purpurea have given
us an insight to the molecular mechanisms and the information will be of importance to molecular biologists. The elucidation of the mechanism of reaction
of dimethylallyltryptophan synthase [77] is worth mentioning. The authors
showed that the prenyl-transfer reaction catalyzed by DMAT-synthase is an
electrophilic aromatic substitution and is mechanistically similar to the
electrophilic alkylation catalyzed by farnesyldiphosphate synthase. The other
significant work was the purification of an enzyme activity capable of synthesis
of d-lysergyl-l-alanyl-l-phenylalanyl-l-proline lactam, the noncyclol precursor of ergotamine [78]. Amino acid activation and lysergic acid activation
domains were identified. Kinetic analysis indicated that under in vivo conditions, d-lysergyl peptide formation is limited by the d-lysergic acid concentration of the cell. The enzyme was also found to be produced constitutively.
Studies on substrate specificities of this enzyme, d-lysergyl peptide synthetase
(LPS), by the same research group showed that the peptide synthetase domain
catalyzing the incorporation of proline appears to be specific for this amino
acid [79].
4
Fermentation Technology
The review [2] describes the large-scale production of ergot alkaloids in bioreactors. It contains information of media, operating conditions, and purification processes. Another review [3] extensively describes the fermentative production of the alkaloids including the basis of the selection of carbon and
nitrogen sources, the addition of trace elements, antifoam agents, the temperature of cultivation, and aeration requirements. This review also mentions
semicontinuous fermentation, scaling up, culture rheology, bioreactor design,
and solid state fermentation. The production of ergot alkaloids covering the
selection of the carbon and nitrogen sources and environmental factors
affecting the fermentative production has also been described [6]. Another
recent review [8] covers the large-scale production of ergot alkaloids.
The effect of some stimulants and depressants of alkaloid production, the use
of oxygen vectors, recent studies on solid state fermentation, and mathematical
modeling, which have not been reviewed earlier, are covered in this section.
The oxidation and cyclization of chanoclavine is dependent on the cultivation conditions. The enzyme, chanoclavine cyclase, reponsible for this biochemical reaction, is a membrane bound enzyme and is thus influenced by
membrane-affecting agents. This was studied with Claviceps purpurea mutant
Progress and Prospects of Ergot Alkaloid Research
13