Jack bean urease (EC 3.5.1.5). I. A simple dry ashing procedure for the microdetermination of trace metals in proteins. The nickel content of urease

1980 ◽  
Vol 58 (6) ◽  
pp. 469-473 ◽  
Author(s):  
Nicholas E. Dixon ◽  
Robert L. Blakeley ◽  
Burt Zerner
Keyword(s):  
Nickel Content ◽  
Spectrophotometric Analysis ◽  
Jack Bean Urease ◽  
Nickel Ions ◽  
Jack Bean ◽  
Determination Of Nickel ◽  
Dry Ashing ◽  
Soluble Species ◽  
Inexpensive Procedure

A simple and inexpensive procedure for determination of microgram quantities of metal ions in proteins is described and tested with nickel and iron. The method involves (a) dry ashing in an oxygen atmosphere at 450–460 °C in Pyrex vessels, (b) conversion of the metal oxides or other compounds to readily soluble species, and (c) spectrophotometric analysis. An improved procedure for the direct spectrophotometric determination of nickel using dimethylglyoxime is accurate to ± 2% or better with samples of 1–5 μg of nickel. These techniques were used to determine that the nickel content of freshly prepared jack bean urease is 2.00 ± 0.12 g-at./96 600 g protein. This corresponds to 2.0 nickel ions per subunit. This result was confirmed by atomic absorption analysis, which also showed that calcium, manganese, cobalt, and iron are not present in significant amounts in urease.

Jack bean urease (EC 3.5.1.5). II. The relationship between nickel, enzymatic activity, and the "abnormal" ultraviolet spectrum. The nickel content of jack beans

1980 ◽  
Vol 58 (6) ◽  
pp. 474-480 ◽  
Author(s):  
Nicholas E. Dixon ◽  
Carlo Gazzola ◽  
Colin J. Asher ◽  
Dennis S. W. Lee ◽  
Robert L. Blakeley ◽  
...  
Keyword(s):  
Enzymatic Activity ◽  
Metal Ions ◽  
Specific Activity ◽  
Nickel Content ◽  
Low Ph ◽  
Ultraviolet Spectrum ◽  
Jack Bean Urease ◽  
Visible Absorption ◽  
Nickel Ions ◽  
Jack Bean

At low pH, EDTA promotes the loss of the tightly bound nickel ions from jack bean urease. The specific activity of soluble enzyme after partial EDTA-promoted inactivation is a linear function of the nickel content. The results are consistent with the presence of 2.0 nickel ions per 97 000-dalton subunit in pure urease. The time scale for loss of enzymatic activity and nickel under these conditions is similar to that for loss of the "abnormal" tail absorption in the ultraviolet and visible absorption spectrum of urease (including the shoulder at ~420 nm). This indicates that nickel in urease is essential for enzymatic activity and establishes that the metal ions are in part responsible for the tail absorption in the ultraviolet spectrum of urease. After partial inactivation in the presence of EDTA either at low pH or in 2.5 M guanidinium chloride at neutral pH, urease did not regain activity in the presence of Ni2+. As yet apourease has not been produced reversibly. Jack bean seeds grown hydroponically without added nickel were low in both urease activity and nickel (10 and 6%, respectively, of parent seeds). Several other metal ions were readily available. This result suggests that metal ions other than nickel cannot substitute for nickel in the formation of normally active urease.

Determination of Tin and Nickel Content in Pyrophosphate Tin-Nickel Alloy Plating Bath

2011 ◽  
Vol 233-235 ◽  
pp. 214-218
Author(s):  
Qiu Ju Geng ◽  
Xue Wei
Keyword(s):  
Standard Deviation ◽  
Nickel Alloy ◽  
Nickel Content ◽  
Plating Bath ◽  
Nickel Ion ◽  
Nickel Ions ◽  
Alloy Plating ◽  
Total Measurement Error ◽  
Analytical Requirements

Tin and nickel ions are in stable complexing form in Pyrophosphate tin-nickel alloy plating bath, this paper uses back-titration of Zn2+ standard solution to determine total amount of tin and nickel ions, and spectrophotometry to determine content of nickel ions in the bath to study interference and elimination methods of co-existing components. The results show that: eliminate the interference of pyrophosphate by heating the solution to hydrolyse and mask Sn4+ and Fe3+ effectively with triethanolamine, the total measurement error is about 0.91%, standard deviation is 0.0141; The recovery of determination for nickel ion content is 99.13%, and standard deviation is 0.0180; The method i-s simple, fast and is able to meet the analytical requirements for controlling the plating quality.

scholarly journals Determination of nickel content in the semimembranosus muscle of pigs produced in Vojvodina

2010 ◽  
pp. 95-102
Author(s):  
Vladimir Tomovic ◽  
Ljiljana Petrovic ◽  
Zarko Kevresan ◽  
Natalija Dzinic ◽  
Marija Jokanovic
Keyword(s):  
Nickel Content ◽  
Absorption Spectrometry ◽  
Developed Countries ◽  
Flame Atomic Absorption ◽  
Determination Of Nickel ◽  
Muscle Tissues ◽  
Semimembranosus Muscle ◽  
Dry Ashing ◽  
General Average ◽  
The Difference

The content of nickel was investigated in the M. semimembranosus of sixty-nine pigs from ten different genetic lines produced in Vojvodina. Nickel was determined by flame atomic absorption spectrometry after mineralization by dry ashing. The difference in the nickel content in the analyzed muscle tissues among different genetic lines of pigs was not significant (P > 0.05). Nickel levels ranged from 12.93 to 80.18 ?g/100 g, with a general average of 32.41 ?g/100 g. The average level of nickel was found to be higher than the levels observed in pork in some developed countries.

scholarly journals Nikiel i jego związki. Metoda oznaczania w powietrzu na stanowiskach pracy

2021 ◽  
Vol 37 (4) ◽  
Author(s):  
Paweł Wasilewski
Keyword(s):  
Occupational Safety ◽  
Nickel Content ◽  
Fine Powder ◽  
High Strength ◽  
Absorption Spectrometry ◽  
A Value ◽  
Safety And Health ◽  
Determination Of Nickel

Nickel due to its physicochemical properties is used to produce high strength, corrosion resistant, temperature resi-stant, high resistance and acid resistant alloys. Nickel in the form of fine powder can induce an allergic response when in contact with the skin, carcinogenic properties have been proven with long-term exposure to nickel dust. According to the proposed directive of the European Parliament No. 2020/0262, a value of maximum allowable concentration (MAC) in a workplace air in Poland for the inhalable fraction should be at 0.05 mg/m3 and for the respirable fraction at 0.01 mg/m3 (2020/0262/COD). The aim of this study was to develop a method for determining nickel in the range of 1/10 ÷ 2 of the MAC. The method is based on gathering nickel aerosol and its compounds contained in the air on a filter, filter mineralization in nitric acid(V) and hydrochloric acid at elevated temperature then determination of nickel content in the sample using atomic absorption spectrometry (AAS) with flame atomization. The method for the determination of nickel is presented in the form of an analytical procedure, which is included in the appendix. This article discusses the problems of occupational safety and health, which are covered by health sciences and environmental engineering.

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