14641-93-1

Usage

Chemical Description

Lactose and
- D -galactopyranosyl-(1
6)-D -galactopyranose are also mentioned in the article.

Uses

Used in Pharmaceutical Industry:
Lactose is used as a diluent for various pharmaceutical applications, including soluble powder dispersions, oral capsules, powder inhalers, and tablets. It is also utilized in lyophilisates and intravenous injections, serving as a drug excipient.
Used in Nutritional Supplements:
Lactose serves as a nutrient for infants and young children, providing essential carbohydrates for their growth and development.
Used in Agricultural Industry:
Lactose is used as a good medium for penicillin production, playing a crucial role in the fermentation process for antibiotic development.

Properties

white or almost white crystalline granules or powder, odorless, slightly sweet. The sweetness of α-lactose is 15% of sucrose. The β-lactose has a higher sweetness than α-lactose. It is soluble in water, insoluble in alcohol, insoluble in ether and chloroform. The lactose monohydrate has a water content of 4.5% -5.5%, while the anhydrous hydrate has a water content of less than 1%. 9.75% (w / v) aqueous solution is isotonic with serum.

Stability and storage conditions

It is easily contaminated by mold in moist conditions (humidity greater than 80%). The color of lactose may turn brown as storage time is extended with moist and heat accelerating this change. Alpha-lactose monohydrate is stable in air and is unaffected by moisture at room temperature, but amorphous form of lactose is dependent on the degree of dryness and may be subject to moisture to be converted to monohydrate. Monohydrate, when heated to 120 ℃, can be converted into anhydrous. A saturated solution of beta-lactose may be precipitated into α-lactose crystals during placement, and the solution has a twisted optical rotation property. Lactose should be placed in airtight container and stored in a cool dry place.

Compatibility & incompatibility

Lactose can reacted with primary amine compounds to produce a brown product; the amorphous lactose is more likely participated into this reaction than crystalline lactose. Lactose has incompatibility with amino acids, aminophylline, amphetamine and isoniazid. Prescription containing tartrate, citrate or acetate, etc., or alkaline lubricants can accelerate the discoloration reaction.

Production process

Use the product of producing cheese or casein - whey as raw material, remove the protein content, followed by concentration, cooling, lactose crystallization and some other processes to obtain the dairy products. Mainly used in food industry, medicine and chemical reagents. Production process: raw whey material- → protein separation - →whey concentration - → cooling and crystallization of lactose - → molasses separation - → lactose washing - → drying (crude lactose) → refining treatment (refined lactose). Raw whey contains whey protein and a small amount of casein, which can be separated through adding line milk to the whey to pH 6.2 ~ 6.5 and simultaneously heating to over 90 ℃ for protein precipitation. Next, the cleared whey is then vacuumed concentrated to 35Be '(70% dry matter, Be' denotes Baume, a specific gravity unit) and cooled to 18-20 ° C for 24 hours to crystallize the lactose. In order to speed up the crystallization process and increase the yield, an appropriate amount of crystallization inducer (lactose powder or crystallized liquid lactose) can be added at the initial stage of crystallization. Crystal should be separated out of molasses using centrifugal dewatering machine and washed with water and finally dried to obtain crude lactose. In the dairy industry, refined lactose is usually produced, but since the crude lactose is yellow and contains more impurities, it needs to be refined before obtaining refined lactose. First, dissolve the crude lactose in warm water; add the decolorant (bone charcoal or activated charcoal) to decolorize; or use ion exchange resin for salt treatment; or use milk protein and calcium chloride for further removing the proteins. Then again apply concentration, drying to make refined lactose. The protein precipitate separated during the production of lactose can be used as a feed, and the separated molasses can also be used as a raw material for feed or lactic acid fermentation.

Lactose intolerance

Lactose digestion and malabsorption could be caused by congenital or secondary lactase deficiency. Lactase (β-galactosidase) catalyzes the hydrolysis of lactose to galactose and glucose, playing an important role in the digestion and absorption of lactose. Most babies contain high amount and high-activity intestinal lactase, being capable of fully digesting a large number of lactose in the diet. At about age 16, intestinal lactase begins to degenerate, and can finally lead to varying degrees of lactase deficiency in adults, which varies according their race. Infant lactase deficiency is mainly due to congenital or hereditary such as congenital intestinal mucosal abnormalities caused by lactase secretion dysfunction; can also be secondary to intestinal diseases such as Crohn's disease, ulcerative colitis, the virus Enteritis causes intestinal mucosa damage. Lactose intolerance can be prevented by removing or avoiding the presence of lactose in the diet. Infants can be feed with lactose-free formula while children can take well-fermented yogurt (in which the lactose has been converted by lactobacillus into lactic acid); adults should avoid drinking a lot of milk with empty stomach. Instead, you can first have a certain amount of other foods to reduce the relative concentration of lactose in the intestine so that bacteria are capable of decomposing it slowly with decomposition products being gradually absorbed.

InChI:InChI=1/C12H22O11/c13-1-3-5(15)6(16)9(19)12(22-3)23-10-4(2-14)21-11(20)8(18)7(10)17/h3-20H,1-2H2/t3-,4-,5+,6+,7-,8-,9-,10-,11+,12+/m1/s1

Upstream product

• 3482-57-3 p-nitrophenyl β-D-cellobioside 
• 2280-44-6 D-Glucose 
• 7585-39-9 β‐cyclodextrin 
• 6401-81-6 maltotriose 
• 1668-09-3 maltopentaose 
• 4202-44-2 malto-octaose 
• 118291-90-0 2-chloro-4-nitrophenol-α-D-maltotrioside 
• 754201-84-8 2,4-dinitrophenyl α-maltoside 
• 3482-57-3 p-nitrophenyl-α-D-glucopyranosyl-(1→4)-O-α-D-glucopyranoside 
• 7493-95-0 4-nitrophenyl α-D-galactoside 
• 499-40-1 melibiose 
• 31208-93-2 o-nitrophenyl α-D-maltosid 

Relevant academic research and scientific papers

Characterization of properties and transglycosylation abilities of recombinant α-galactosidase from cold-adapted marine bacterium pseudoalteromonas KMM 701 and its C494N and D451A mutants

A novel wild-type recombinant cold-active α-D-galactosidase (α-PsGal) from the cold-adapted marine bacterium Pseudoalteromonas sp. KMM 701, and its mutants D451A and C494N, were studied in terms of their structural, physicochemical, and catalytic properties. Homology models of the three-dimensional α-PsGal structure, its active center, and complexes with D-galactose were constructed for identification of functionally important amino acid residues in the active site of the enzyme, using the crystal structure of the α-galactosidase from Lactobacillus acidophilus as a template. The circular dichroism spectra of the wild α-PsGal and mutant C494N were approximately identical. The C494N mutation decreased the efficiency of retaining the affinity of the enzyme to standard p-nitrophenyl-α-galactopiranoside (pNP-α-Gal). Thin-layer chromatography, matrix-assisted laser desorption/ionization mass spectrometry, and nuclear magnetic resonance spectroscopy methods were used to identify transglycosylation products in reaction mixtures. α-PsGal possessed a narrow acceptor specificity. Fructose, xylose, fucose, and glucose were inactive as acceptors in the transglycosylation reaction. α-PsGal synthesized -α(1→6)- and -α(1→4)-linked galactobiosides from melibiose as well as -α(1→6)- and -α(1→3)-linked p-nitrophenyl-digalactosides (Gal2-pNP) from pNP-α-Gal. The D451A mutation in the active center completely inactivated the enzyme. However, the substitution of C494N discontinued the Gal-α(1→3)-Gal-pNP synthesis and increased the Gal-α(1→4)-Gal yield compared to Gal-α(1→6)-Gal-pNP.

The kinetics of p-nitrophenyl-β-d-cellobioside hydrolysis and transglycosylation by Thermobifida fusca Cel5Acd

The hydrolysis of p-nitrophenyl-β-1,4-cellobioside (pNP-G2) by the catalytic domain of the retaining-family 5-2 endocellulase Cel5A from Thermobifida fusca (Cel5Acd) was studied. The dominant reaction pathway involves hydrolysis of the aglyconic bond, producing cellobiose (G2) and a 'reporter' species p-nitrophenol (pNP), which was monitored spectrophotometrically to track the reaction. We also detected the production of cellotriose (G3) and p-nitrophenyl-glucoside (pNP-G1), confirming the presence of a competing transglycosylation pathway. We use a mechanistic model of hydrolysis and transglycosylation to derive an expression for the rate of pNP-formation as a function of enzyme concentration, substrate concentration, and several lumped kinetics parameters. The derivation assumes that the quasi-steady-state assumption (QSSA) applies for three intermediate species in the mechanism; we determine conditions under which this assumption is rigorously justified. We integrate the rate expression and compare its integral form to pNP-versus-time data collected for a range of enzyme and substrate concentrations. The integral comparison gives a stringent test of the mechanistic model, and it serves to quantify the lumped kinetics parameters with good statistical precision, particularly a previously unidentified parameter that determines the selectivity of hydrolysis versus transglycosylation. The integrated rate expression accounts well for pNP-versus-time data under all circumstances we have investigated.

Synthesis and characterization of bis(glycosylamino)benzenes based on reducing disaccharides

Synthesis of bis(glycosylamino)benzenes, derived from disaccharides lactose, maltose, and cellobiose, by direct condensation and their characterization are described.

Synthesis and characterisation of novel chromogenic substrates for human pancreatic α-amylase

Derivatives of maltose and maltotriose were chemically synthesised as substrates for human pancreatic α-amylases and subjected to kinetic analysis. Rates measured were shown to reflect both hydrolysis and transglycosylation reactions. 4-O-Methylated derivatives of these substrates underwent only hydrolysis, thereby simplifying kinetic analyses. These modified substrates may be used for the detection and kinetic analysis of α-amylases, and are useful in rapidly screening for novel α-amylase inhibitors and for subsequent kinetic characterisation.

Study of the action of human salivary alpha-amylase on 2-chloro-4-nitrophenyl α-maltotrioside in the presence of potassium thiocyanate

The degradation mechanism of a synthetic substrate, 2-chloro-4-nitrophenyl α-maltotrioside (CNP-G3), by human salivary alpha-amylase (HSA) was investigated by kinetic and product analyses. It was observed that the enzyme attacked the various CNP-maltooligosaccharides (CNP-G3, to CNP-G6) releasing free CNP. Addition of 500 mM potassium thiocyanate (KSCN) was also found to greatly increase the rates of CNP-release. It was the fastest with CNP-G3, and, in the presence of KSCN, was almost comparable to that of degradation of maltopentaose (G5). On the other hand, addition of KSCN decreased the rate of cleavage between glucan-glucan bonds in maltopentaose. Product analysis showed that KSCN addition altered the cleavage distribution which occurred 100% at the bond between CNP and G3, and that product distribution of free CNP was largely dependent on substrate concentration. Formation of CNP-G6, a larger product than the original substrate CNP-G3, was found to be present in the digest at high concentrations of substrate and in the presence of KSCN. Based on these results, a degradation pathway for CNP-G3 involving transglycosylation besides direct hydrolysis is proposed. The increase of the CNP-release by the addition of KSCN would result from a corresponding increase in the interaction between the CNP moiety and the corresponding subsite near the catalytic site, as well as the enhancement of the catalytic efficiency.

Subsite mapping of porcine pancreatio alpha-amylase I and II using 4-nitrophenyl-α-maltooligosaccharides

The catalytic efficiency (kcat/Km) and the cleaved bond distribution for the nitrophenylated maltooligosaccharides, p-NPGIcn (2n7) hydrolysed by porcine pancreatic alpha-amylase isozymes I and II were determined. the subsite affinities (Ai) were calculated from the p-NPGlcn (4n7) hydrolysis data.Five subsites (-3 to 2) bind glucosidic residues with a positive affinity.No additional subsites could be detected both at the reducing end (3,4,5)and at the nonreducing end (-4,-5,-6).The energetic profiles of both isozymes are similar.The energetic profile of PPA differs from other alpha-amylases by having both a small number of subsites, and a catalytic subsite with a high positive affinity.Excellent agreement was found between observed catalytic efficiency values and those calculated from the subsite affinities. Keywords: alpha-Amylase isozymes; Active centre; Subsite structure; Energetic profile; Porcine pencreatic alpha-amylaseKeywords: alpha-Amylase isozymes; Active centre; Subsite structure; Energetic profile; Porcine Pancreatic alpha-amylase

Stereoselective Thioglycoside Syntheses. Part 6. Aryl 4-Thiomaltooligosacchrides as Chromogenic Substrates for Kinetic Studies with α-Amylase

Nucleophilic bimolecular substitution, of either o- or p-nitrophenyl 2,3,6-tri-O-benzoyl-4-O-trifluoromethylsulphonyl-α-D-galactopyranoside (1) or (2) with the sodium salt of 1-thio-α-D-glucopyranose in hexamethylphosphoramide afforded, after the usual deprotection sequences, o- and p-nitrophenyl 4-thio-α-maltosides (7) and (8).A similar synthetic scheme with (1) and the 1-α-thiolate of 4-thiomaltose (12) led to o-nitrophenyl 4,4'-dithio-α-maltotrioside (15).These 4-thio-oligosaccharides and their corresponding oxygen analogues were used, in comparative assays, as chromogenic substrates with porcine and human pancreatic α-amylases.In both series, enzymic velocity was higher for the maltotrioside derivatives than for the maltodisaccharides. o-Nitrophenyl glycosides behave as better substrates than the corresponding para isomers.Replacement of intersaccharide oxygen atoms by sulphur increased slightly the Michaelis constant, but had a negative effect on the hydrolysis rate.As a consequence, 4-thiomaltosyloligosaccharides were less sensitive substrates for pig pancreatic α-amylase as compared with their O-glycosyl counterparts.However, as the former class of compounds is split exclusively at the chromogenic site, they appear to be substrates of interest for direct kinetic studies with α-amylases.