Studies on carbohydrate-metabolizing enzymes. 6. The action of potato phosphorylase (P-enzyme) on starch-type polysaccharides

Am, Liddle; Dj, Manners; Wright, A C

doi:10.1042/bj0800304

Cited by 23 publications

(3 citation statements)

References 14 publications

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“…For example, the plastidic SP enzymes from potato tuber (Liddle et al, 1961), spinach leaf (Shimomura et al, 1982), and sweet corn (Lee and Braun, 1973) prefer amylopectin as a substrate to glycogen, which is a more highly branched ␣-glucan. Indeed the maize amyloplast stromal 112-kD SP preferred amylopectin as a substrate when compared with glycogen.…”

Section: Discussionmentioning

confidence: 99%

Identification of the Maize Amyloplast Stromal 112-kD Protein as a Plastidic Starch Phosphorylase,

Wasserman

et al. 2001

Plant Physiology

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Amyloplast is the site of starch synthesis in the storage tissue of maize (Zea mays). The amyloplast stroma contains an enriched group of proteins when compared with the whole endosperm. Proteins with molecular masses of 76 and 85 kD have been identified as starch synthase I and starch branching enzyme IIb, respectively. A 112-kD protein was isolated from the stromal fraction by sodium dodecyl sulfate-polyacrylamide gel electrophoresis and subjected to tryptic digestion and amino acid sequence analysis. Three peptide sequences showed high identity to plastidic forms of starch phosphorylase (SP) from sweet potato, potato, and spinach. SP activity was identified in the amyloplast stromal fraction and was enriched 4-fold when compared with the activity in the whole endosperm fraction. Native and sodium dodecyl sulfate-polyacrylamide gel electrophoresis analyses showed that SP activity was associated with the amyloplast stromal 112-kD protein. In addition, antibodies raised against the potato plastidic SP recognized the amyloplast stromal 112-kD protein. The amyloplast stromal 112-kD SP was expressed in whole endosperm isolated from maize harvested 9 to 24 d after pollination. Results of affinity electrophoresis and enzyme kinetic analyses showed that the amyloplast stromal 112-kD SP preferred amylopectin over glycogen as a substrate in the synthetic reaction. The maize shrunken-4 mutant had reduced SP activity due to a decrease of the amyloplast stromal 112-kD enzyme.

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Section: Discussionmentioning

confidence: 99%

Identification of the Maize Amyloplast Stromal 112-kD Protein as a Plastidic Starch Phosphorylase,

Wasserman

et al. 2001

Plant Physiology

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“…In Hordeum vulgare , PHO1 also confirmed the synthetic activity in developing endosperm, which was highest at 12 DAA and gradually decreased afterward, but the activity does not correlate with the expression level, possibly because of substrate preferences. The preference of substrate by PHO1 has been intensively investigated in various plant species [ 8 , 49 , 68 , 69 , 70 , 71 ]. PHO1 in Ipomoea batatas showed low binding affinity toward starch (high molecular weight) and high binding affinity towards MOs (low molecular weight) [ 68 ].…”

Section: Synthetic and Phosphorolytic Activity Of Phosphorylasementioning

confidence: 99%

“…In contrast, PHO1 in Zea mays showed high binding affinity toward high molecular weight compounds and low binding affinity toward low molecular weight compounds [ 69 ]. In Zea mays [ 8 ], Solanum tuberosum [ 70 ], and Spinacia oleracea [ 71 ] synthetic activity of PHO1 was reported to be high when amylopectin was used as a substrate in comparison to highly branched glycogen. In Solanum tuberosum L80 insertion was reported to block the binding affinity of PHO1 with high molecular weight compounds [ 68 ].…”

Section: Synthetic and Phosphorolytic Activity Of Phosphorylasementioning

confidence: 99%

Molecular Functions and Pathways of Plastidial Starch Phosphorylase (PHO1) in Starch Metabolism: Current and Future Perspectives

Shoaib

Liu

Ali

et al. 2021

IJMS

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Starch phosphorylase is a member of the GT35-glycogen-phosphorylase superfamily. Glycogen phosphorylases have been researched in animals thoroughly when compared to plants. Genetic evidence signifies the integral role of plastidial starch phosphorylase (PHO1) in starch biosynthesis in model plants. The counterpart of PHO1 is PHO2, which specifically resides in cytosol and is reported to lack L80 peptide in the middle region of proteins as seen in animal and maltodextrin forms of phosphorylases. The function of this extra peptide varies among species and ranges from the substrate of proteasomes to modulate the degradation of PHO1 in Solanum tuberosum to a non-significant effect on biochemical activity in Oryza sativa and Hordeum vulgare. Various regulatory functions, e.g., phosphorylation, protein–protein interactions, and redox modulation, have been reported to affect the starch phosphorylase functions in higher plants. This review outlines the current findings on the regulation of starch phosphorylase genes and proteins with their possible role in the starch biosynthesis pathway. We highlight the gaps in present studies and elaborate on the molecular mechanisms of phosphorylase in starch metabolism. Moreover, we explore the possible role of PHO1 in crop improvement.

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Higher Plant Phosphorylases

Tanizawa

Mori

Tagaya

et al. 1994

Molecular Aspects of Enzyme Catalysis

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Studies on carbohydrate-metabolizing enzymes. 6. The action of potato phosphorylase (P-enzyme) on starch-type polysaccharides

Cited by 23 publications

References 14 publications

Identification of the Maize Amyloplast Stromal 112-kD Protein as a Plastidic Starch Phosphorylase,

Identification of the Maize Amyloplast Stromal 112-kD Protein as a Plastidic Starch Phosphorylase,

Molecular Functions and Pathways of Plastidial Starch Phosphorylase (PHO1) in Starch Metabolism: Current and Future Perspectives

Higher Plant Phosphorylases

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