Sucrase

Sucrases are digestive enzymes that catalyze the hydrolysis of sucrose to its component monosaccharides, fructose and glucose. One form, sucrase-isomaltase, is secreted in the small intestine on the brush border.^[1] The enzyme invertase, which occurs more commonly in plants, fungi and bacteria, also hydrolyzes sucrose (and other fructosides) but by a different mechanism: it is a fructosidase, whereas sucrase is a glucosidase.^[2]

Types

EC 3.2.1.10 is sucrase-isomaltase
EC 3.2.1.48 is sucrose alpha-glucosidase

Physiology

Sucrose intolerance (also known as congenital sucrase-isomaltase deficiency (CSID), genetic sucrase-isomaltase deficiency (GSID), or sucrase-isomaltase deficiency) occurs when sucrase is not being secreted in the small intestine. With sucrose intolerance, the result of consuming sucrose is excess gas production and often diarrhea and malabsorption. Lactose intolerance is a similar condition that reflects an individual's inability to hydrolyze the disaccharide lactose.

Sucrase is secreted by the tips of the villi of the epithelium in the small intestine. Its levels are reduced in response to villi-blunting events such as celiac sprue and the inflammation associated with the disorder. The levels increase in pregnancy, lactation, and diabetes as the villi hypertrophy.

Use in chemical analysis

Sucrose is a non-reducing sugar, so will not test positive with Benedict's solution. To test for sucrose, the sample is treated with sucrase. The sucrose is hydrolysed into glucose and fructose, with glucose being a reducing sugar, which in turn tests positive with Benedict's solution.^{[citation needed]}.

In other species

Cedar waxwings (Bombycilla cedrorum) and American robins (Turdus migratorius) have evolved to lose this enzyme due to their insectivorous and frugivorous diets.^[3] This absence produces digestive difficulty if challenged with unusual amounts of the sugar.^[3]

References

^ Tortora, Gerard (2014). Principles of Anatomy & Physiology 14th edition. USA: Wiley. pp. 924. ISBN 978-1-118-34500-9.
^ Hubert Schiweck; Margaret Clarke; Günter Pollach (2007). "Sugar". Ullmann's Encyclopedia of Industrial Chemistry. Weinheim: Wiley-VCH. doi:10.1002/14356007.a25_345.pub2. ISBN 978-3-527-30673-2.
^ ^a ^b Martínez del Rio, C.; Baker, H. G.; Baker, I. (1992). "Ecological and evolutionary implications of digestive processes: Bird preferences and the sugar constituents of floral nectar and fruit pulp". Experientia. 48 (6). Birkhäuser: 544–551. doi:10.1007/bf01920237. ISSN 0014-4754. S2CID 25707787.

External links

Sucrase at the U.S. National Library of Medicine Medical Subject Headings (MeSH)

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[1] Tortora, Gerard (2014). Principles of Anatomy & Physiology 14th edition. USA: Wiley. pp. 924. ISBN 978-1-118-34500-9.

[Ullmann-2] Hubert Schiweck; Margaret Clarke; Günter Pollach (2007). "Sugar". Ullmann's Encyclopedia of Industrial Chemistry. Weinheim: Wiley-VCH. doi:10.1002/14356007.a25_345.pub2. ISBN 978-3-527-30673-2.

[Rio-et-al-1992-3] Martínez del Rio, C.; Baker, H. G.; Baker, I. (1992). "Ecological and evolutionary implications of digestive processes: Bird preferences and the sugar constituents of floral nectar and fruit pulp". Experientia. 48 (6). Birkhäuser: 544–551. doi:10.1007/bf01920237. ISSN 0014-4754. S2CID 25707787.

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v t e Enzymes
Activity	Active site Binding site Catalytic triad Oxyanion hole Enzyme promiscuity Diffusion-limited enzyme Cofactor Enzyme catalysis
Regulation	Allosteric regulation Cooperativity Enzyme inhibitor Enzyme activator
Classification	EC number Enzyme superfamily Enzyme family List of enzymes
Kinetics	Enzyme kinetics Eadie–Hofstee diagram Hanes–Woolf plot Lineweaver–Burk plot Michaelis–Menten kinetics
Types	EC1 Oxidoreductases (list) EC2 Transferases (list) EC3 Hydrolases (list) EC4 Lyases (list) EC5 Isomerases (list) EC6 Ligases (list) EC7 Translocases (list)