Anorganische Stickstoffverbindungen I. Zersetzungsmechanismus wässriger Lösungen des Natriumsalzes der Nitrohydroxylaminsäure

Donors of HNO

“…In concentrated acid, not only is the rate of Angeli's salt decomposition significantly accelerated [3,62], but NO becomes the only nitrogen-containing end product [61,68]. The alteration in product formation from HNO and nitrite to NO alone occurs at pH 3 [3] (or at higher pH in the presence of excess nitrite [4]), and although the low pH mechanism has been examined to various degrees by numerous researchers, it has yet to be fully elucidated experimentally.…”

“…The thermal decomposition of Angeli's salt is first-order [61] and pH-dependent [3,62]. The decay profile is reflective of the pK a s of 2.5 and 9.7 for oxyhyponitrous acid (H 2 N 2 O 3 ) [63] in that the rate progressively accelerates as solution alkalinity declines to pH 8, plateaus from pH 8-4 (6.8 × 10 -4 s -1 at 25°C and 4-5 × 10 -3 s -1 at 37°C [4,64]), and then resumes acceleration below pH 4.…”

A mixed-metal derivative of laccase containing mercury(II) in the type 1 binding site

“…As a further check on the integrity of type 2 copper, we have confirmed that the spectrum of the mercury derivative and the type 2 signal of native lacease suffer the same changes when fluoride or azide is added. 3 The ligand hyperfine splitting, which is resolved in Figure 1C, strongly suggests at least one nitrogen ligand is present in this site, a more precise count being precluded by the convolution of the ligand hyperfine splitting with that of the metal. The ligand hyperfine structure is barely perceptible in Figure 1B where severe overlap with the type 1 signal occurs.…”

“…The imidazole moiety from a histidine residue has previously been implicated as a ligand of the type 2 site by spin-echo methods.8 (5) For a description of the three distinct binding sites of lacease, see ref 798-802. cWhen apolaccase is remetalated by using only Cu(I), 3.8 ± 0.3 equiv of copper are taken up and an M80/M33 absorbance ratio of 22 ± 3 is obtained. dMetal to protein ratios; total protein was determined by a modification of the biuret method using native lacease as a standard.…”

“…HN203" -HNO + NOf (2) 2HNO -N20 + H20 (3) We have previously established that hemoglobin is a particularly sensitive reagent for the detection of free nitric oxide generated from nitric oxide donors.9 Association of deoxyhemoglobin (Hb) with nitric oxide occurs with a rate constant of 2 X 107 M"1 s"1 and is essentially irreversible. 10…”