Microwave-enhanced reductive amination via Schiff's base formation for block copolymer synthesis

2012 ◽  
Vol 87 (4) ◽  
pp. 2740-2744 ◽  
Author(s):  
Mohit S. Verma ◽  
Frank X. Gu
Keyword(s):  
Block Copolymer ◽  
Reductive Amination ◽  
Schiff’S Base ◽  
Base Formation

scholarly journals Lipid Metabolic Events Underlying the Formation of the Corneocyte Lipid Envelope

2021 ◽  
pp. 1-13
Author(s):  
Philip W. Wertz
Keyword(s):  
Stratum Corneum ◽  
Outer Surface ◽  
Barrier Function ◽  
Skin Surface ◽  
Schiff’S Base ◽  
Cornified Envelope ◽  
Epoxy Alcohol ◽  
Viable Epidermis ◽  
Transglutaminase 1 ◽  
Base Formation

Cornified cells of the stratum corneum have a monolayer of an unusual lipid covalently attached to the outer surface. This is referred to as the corneocyte lipid envelope (CLE). It consists of a monolayer of ω-hydroxyceramides covalently attached to the outer surface of the cornified envelope. The CLE is essential for proper barrier function of the skin and is derived from linoleate-rich acylglucosylceramides synthesized in the viable epidermis. Biosynthesis of acylglucosylceramide and its conversion to the cornified envelope is complex. Acylglucosylceramide in the bounding membrane of the lamellar granule is the precursor of the CLE. The acylglucosylceramide in the limiting membrane of the lamellar granule may be oriented with the glucosyl moiety on the inside. Conversion of the acylglucosylceramide to the CLE requires removal of the glucose by action of a glucocerebrosidase. The ester-linked fatty acid may be removed by an as yet unidentified esterase, and the resulting ω-hydroxyceramide may become ester linked to the outer surface of the cornified envelope through action of transglutaminase 1. Prior to removal of ester-linked fatty acids, linoleate is oxidized to an epoxy alcohol through action of 2 lipoxygenases. This can be further oxidized to an epoxy-enone, which can spontaneously attach to the cornified envelope through Schiff’s base formation. Mutations of genes coding for enzymes involved in biosynthesis of the CLE result in ichthyosis, often accompanied by neurologic dysfunction. The CLE is recognized as essential for barrier function of skin, but many questions about details of this essentiality remain. What are the relative roles of the 2 mechanisms of lipid attachment? What is the orientation of acylglucosylceramide in the bounding membrane of lamellar granules? Some evidence supports a role for CLE as a scaffold upon which intercellular lamellae unfold, but other evidence does not support this role. There is also controversial evidence for a role in stratum corneum cohesion. Evidence is presented to suggest that covalently bound ω-hydroxyceramides serve as a reservoir for free sphingosine that can serve in communicating with the viable epidermis and act as a potent broad-acting antimicrobial at the skin surface. Many questions remain.

Schiff's base formation rater than molecular association between acetone and 3-amino-6-methoxypyridine

1993 ◽  
Vol 31 (7) ◽  
pp. 685-688 ◽  
Author(s):  
John Maguire ◽  
David G. Morris ◽  
David S. Rycroft ◽  
F. S. Ortiz
Keyword(s):  
Molecular Association ◽  
Schiff’S Base ◽  
Base Formation

Insights into the Maillard reaction. The mechanism of Schiff's base formation from the reaction force perspective

2009 ◽  
Vol 107 (15) ◽  
pp. 1587-1596 ◽  
Author(s):  
Patricio Flores-Morales ◽  
Soledad Gutiérrez-Oliva ◽  
Eduardo Silva ◽  
Alejandro Toro-Labbé
Keyword(s):  
Maillard Reaction ◽  
Reaction Force ◽  
Schiff’S Base ◽  
Base Formation

scholarly journals Ultrastructural cytochemistry of p-N,N-dimethylamino-beta-phenethylamine (DAPA) oxidation reactions.

1976 ◽  
Vol 24 (3) ◽  
pp. 527-539 ◽  
Author(s):  
W A Shannon ◽  
H L Wasserkrug ◽  
R E Plapinger ◽  
A M Seligman
Keyword(s):  
Oxidation Reaction ◽  
Amine Oxidase ◽  
Oxidative Polymerization ◽  
Tetrazolium Salt ◽  
Oxidation Reactions ◽  
Reaction Products ◽  
Schiff’S Base ◽  
Tetrazolium Chloride ◽  
Pig Kidney ◽  
Base Formation

The ultracytochemical localization of amine oxidase (AO) activity is demonstrated with a new substrate, p-N,N-dimethylamino-beta-phenethylamine (DAPA). DAPA was designed to yield a stronger reducing agent on oxidation by monoamine oxidase (MAO) than is obtained from the MAO substrate, tryptamine, upon oxidation. Thus MAO and possibly other oxidase(s) can be demonstrated with DAPA and the tetrazolium salt, 2-(2'-benzothiazolyl)-5-styryl-3-(4'-phthalhydrazidyl) tetrazolium chloride (BSPT). The latter is a nonosmiophilic tetrazolium salt which is reduced to an osmiophilic formazan. In addition, DAPA itself demonstrates AO activity ultracytochemically with and without BSPT. We speculate that either oxidative polymerization of DAPA or Schiff's base formation with protein after aldehyde formation is responsible for the latter reaction, which is made permanent for ultracytochemical localization by osmication at a later step. DAPA oxidation reaction products are demonstrated in guinea pig kidney, specifically in the endoplasmic reticulum, nuclear envelope and mitochondrial outer compartments and cristae. Differences in reaction product characteristics and localization in relation to formaldehyde fixation and the localization of reaction product in mitochondrial cristae, as well as outer compartments, suggest that DAPA oxidation is mediated through one or more MAOs and possible other oxidases.

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