Mechanism of Borate Inhibition of Diphenol Oxidation by Tyrosinase

Yasunobu, Kerry T.; Norris, Earl R.

doi:10.1016/s0021-9258(18)70830-2

Cited by 29 publications

(3 citation statements)

References 5 publications

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“…Regarding stability, it is accepted that the kinetics of borate ester formation with catechols from borates and boronic acid in vitro allows a rapid and effective synthesis of the corresponding catechol-borate complexes (Yasunobu and Norris, 1957;Roy and Brown, 2007;Tsuyumoto et al, 2007, Bernardini et al, 2009Ketuly and Hadi, 2010;Pereira Silva et al, 2020). It is commonly accepted that borate esters of aliphatic cis-diols, catechols and substituted catechols with borates or boronic acids are reasonably stable under non-dramatic hydrolytic conditions, mainly those from catechols (Roy and Brown, 2007;Bernardini et al, 2009;Ketuly and Hadi, 2010).…”

Section: Resultsmentioning

confidence: 99%

In vivo polymerization of the dopamine-borate melanin precursor: A proof-of-concept regarding boron neutron-capture therapy for melanoma

Stockert¹,

ROMERO²,

Felix-Pozzi³

et al. 2023

Biocell

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The 10 boron neutron-capture therapy (BNCT) is an emerging antitumoral method that shows increasing biomedical interest. BNCT is based on the selective accumulation of the 10 boron isotope within the tumor, which is then irradiated with low-energy thermal neutrons, generating nuclear fission that produces 7 lithium, 4 helium, and γ rays. Simple catechol-borate esters have been rather overlooked as precursors of melanin biosynthesis, and therefore, a proof-of-concept approach for using dopamine-borate (DABO) as a suitable boron-containing candidate for potential BNCT is presented here. DABO can spontaneously oxidize and autopolymerize in vitro, giving a soluble, eumelaninlike brown-black poly-DABO product. Melanotic melanoma cell cultures treated with 1 mM DABO for 24 and 48 h were viable and showed no signs of damage or cell death. The stability and possible trans-esterification of DABO is shortly discussed. Chemical calculations and quantitative structure-activity relationships (QSAR) analysis of DABO and the BNCT agent BPA indicated that they should be cell permeant and accumulate within lysosomes and melanosomes. Molecular modeling allows visualization of both the DABO precursor and the structure of a borate derivative of the proposed catechol-porphycene model for eumelanin, showing interesting features from molecular orbital calculations. The main difference between DABO and other agents, such as BPA, is that it is not a boronic acid nor a boron cluster. This simple catechol-borate ester (protected from oxidation and blackening) could be administrated to living cells and organisms, in which biosynthesis of boron-melanin in melanoma melanocytes can lead to improved BNCT.

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Section: Resultsmentioning

confidence: 99%

In vivo polymerization of the dopamine-borate melanin precursor: A proof-of-concept regarding boron neutron-capture therapy for melanoma

Stockert¹,

ROMERO²,

Felix-Pozzi³

et al. 2023

Biocell

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“…The chelation of boronic acids by catechols has been known for at least 100 years (1). Ligand binding studies have determined that catechols form primarily 1:1 complexes with borate (2, 3); the complexes have stability constants ranging from 104 to 106 and exhibit maximal association at pH 8 to 9 (2)(3)(4)(5)(6). Today the chelation of boronic acids is commonly exploited to separate or purify catecholic compounds by affinity chromatography (7)(8)(9) and electrophoresis (10)(11)(12).…”

mentioning

confidence: 99%

“…Given the significant ultraviolet absorbance of (catecholato)borate complexes, however, the chelation would also seem to offer distinct advantages as an assay method for catechols and/or borate. This potential has only been examined for a handful of catechols including various flavanoids (13), 3,4-0003-2700/84/0356-1935$01.50/0 dihydroxy-L-phenylalanine (Dopa) (6), and 4-nitrocatechol (5).…”

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confidence: 99%

Determination of (catecholato)borate complexes using difference spectrophotometry

Waite¹

1984

Anal. Chem.

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Supramolecular β‐Sheet Suckerin–Based Underwater Adhesives

Deepankumar

Lim

Polte

et al. 2020

Adv Funct Materials

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Nature has evolved several molecular strategies to ensure adhesion in aqueous environments, where artificial adhesives typically fail. One recentlyunveiled molecular design for wet-resistant adhesion is the cohesive cross-β structure characteristic of amyloids, complementing the well-established surface-binding strategy of mussel adhesive proteins based on 3,4-l-dihydroxyphenylalanine (Dopa). Structural proteins that self-assemble into cross β-sheet networks are the suckerins discovered in the sucker ring teeth of squids. Here, light is shed on the wet adhesion of cross-β motifs by producing recombinant suckerin-12, naturally lacking Dopa, and investigating its wet adhesion properties. Surprisingly, the adhesion forces measured on mica reach 70 mN m −1 , exceeding those measured for all mussel adhesive proteins to date. The pressure-sensitive adhesion of artificial suckerins is largely governed by their cross-β motif, as evidenced using control experiments with disrupted cross-β domains that result in complete loss of adhesion. Dopa is also incorporated in suckerin-12 using a residue-specific incorporation strategy that replaces tyrosine with Dopa during expression in Escherichia coli. Although the replacement does not increase the long-term adhesion, it contributes to the initial rapid contact and enhances the adsorption onto model oxide substrates. The findings suggest that suckerins with supramolecular cross-β motifs are promising biopolymers for wet-resistant adhesion.

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Mechanism of Borate Inhibition of Diphenol Oxidation by Tyrosinase

Cited by 29 publications

References 5 publications

In vivo polymerization of the dopamine-borate melanin precursor: A proof-of-concept regarding boron neutron-capture therapy for melanoma

In vivo polymerization of the dopamine-borate melanin precursor: A proof-of-concept regarding boron neutron-capture therapy for melanoma

Determination of (catecholato)borate complexes using difference spectrophotometry

Supramolecular β‐Sheet Suckerin–Based Underwater Adhesives

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