**2. Identification of glycoproteins that bind pancreatic α-amylase in the small intestinal BBM**

In the small intestine, epithelial cells in the luminal villi have a brush border on the surface, and alkaline phosphatase and other membrane-type digestive enzymes

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**Figure 1.**

*Binding of pancreatic α-amylase to pig duodenum BBM.*

*Regulatory Functions of α-Amylase in the Small Intestine Other than Starch Digestion…*

are localized on the BBM. The BBM is covered with a glycocalyx composed of glycoproteins and proteoglycans [10, 12]. Lectin staining of rat small intestine tissue revealed that rat small intestinal BBM expresses glycoproteins having complex, high-mannose *N*-glycans, and core 1 *O*-glycans including NeuAcα2-6Gal/GalNAc, and Galβ1-3Gal [9]. It is reported that *N*-glycans of glycoproteins on the surface of

Previous reports have shown that pancreatic α-amylase binds to the *N*-glycans of purified glycoproteins [5], but it has not been confirmed whether or not pancreatic α-amylase binds to glycoproteins on small intestinal BBM. Furthermore, which glycoproteins bind to the pancreatic α-amylase and what role they play in interactions with the α-amylase were unknown. This study demonstrated the binding of α-amylase to pig small intestinal BBM by immunostaining, and identified the

Tissue sections of pig duodenum were immunostained with an anti-pancreatic α-amylase antibody. Entire duodenal tissue sections were stained with the pancreatic α-amylase antibody when there was a large amount of food in the stomach (during non-fasting), but hardly stained when there was little in the stomach (during fasting) [14]. The localization of exogenous pancreatic α-amylase was examined by staining a 1-cm section of the duodenum of a fasted pig with the pancreatic α-amylase antibody. Tissue sections fixed in formalin and embedded in paraffin were immunostained to detect pancreatic α-amylase. The duodenal sections were agitated in pancreatic α-amylase solution at 4°C. As a result, pancreatic α-amylase bound to the BBM, which is the upper end of the duodenal epithelium (**Figure 1**), and α-amylase staining increased in a time-dependent manner with agitation. Mannan inhibited the binding of pancreatic α-amylase to BBM duodenum sections incubated in α-amylase solution for 30 min. On the other hand, galactan and colominic acid inhibited binding of α-amylase to BBM after 10 min of agitation, but did not inhibit binding of α-amylase to BBM agitated for 30 min (data not shown) [14]. Pancreatic α-amylase bound to duodenum BBM, and its binding was inhibited by

porcine intestine have more complex types than those on the rats [13].

glycoproteins that bind α-amylase in the pig small intestinal BBM [14].

**2.1 Binding of pancreatic α-amylase to small intestinal BBM**

*DOI: http://dx.doi.org/10.5772/intechopen.92660*

*Regulatory Functions of α-Amylase in the Small Intestine Other than Starch Digestion… DOI: http://dx.doi.org/10.5772/intechopen.92660*

are localized on the BBM. The BBM is covered with a glycocalyx composed of glycoproteins and proteoglycans [10, 12]. Lectin staining of rat small intestine tissue revealed that rat small intestinal BBM expresses glycoproteins having complex, high-mannose *N*-glycans, and core 1 *O*-glycans including NeuAcα2-6Gal/GalNAc, and Galβ1-3Gal [9]. It is reported that *N*-glycans of glycoproteins on the surface of porcine intestine have more complex types than those on the rats [13].

Previous reports have shown that pancreatic α-amylase binds to the *N*-glycans of purified glycoproteins [5], but it has not been confirmed whether or not pancreatic α-amylase binds to glycoproteins on small intestinal BBM. Furthermore, which glycoproteins bind to the pancreatic α-amylase and what role they play in interactions with the α-amylase were unknown. This study demonstrated the binding of α-amylase to pig small intestinal BBM by immunostaining, and identified the glycoproteins that bind α-amylase in the pig small intestinal BBM [14].
