A Year of (Bio)chemical Elements

Rounding out the year
with nickel and zinc

Quira Zeidan
December 01, 2019

To complete our celebration of the 150th anniversary of Dmitri Mendeleev’s periodic table, we look at nickel and zinc, two metallic elements with chemical symbols Ni and Zn and atomic numbers 28 and 30, respectively.

Nickel and ZincThis ribbon diagram shows the 3D structure of the enzyme urease in coordination with two nickel ions depicted in green.E. Jabri et al/Wikimedia Commons

Nickel can exist in oxidation states ranging from -2 to +4. The most abundant — Ni+2 — combines with common anions such as sulfate, sulfide, carbonate, nitrate and hydroxide. In contrast, zinc predominates in the oxidation +2 almost exclusively, acting as a strong reducing agent. Zinc forms binary compounds with most nonmetal and metalloid elements with the exception of noble gases.

Nickel is produced with iron in the final stages of nuclear reactions during violent explosions deep inside supergiant stars. As a result, these two elements are mixed abundantly in the interior of meteorites. The astrophysical origin of zinc is not entirely understood, but it might have involved the asymmetric explosion of the universe’s earliest supernova.

Nickel makes up only 0.008% of the Earth’s crust and occurs often as an alloy with iron in the planet’s core. It also exists in minerals in combination with sulfur and arsenic. Zinc is the 24th most common element in the Earth’s crust, where it is found primarily as zinc sulfide and as a binary alloy with metals including aluminum, gold, iron, lead, silver and nickel. Mineral weathering disperses small amounts of zinc into soil, seawater and the atmosphere.

Both nickel and zinc are essential for life and are present in many organisms. Nickel is recognized and transported into the cell by a variety of mechanisms: nonspecific influx across membrane proteins in bacteria and yeast, high-affinity uptake via transporters and permeases in certain bacteria, and incorporation through channels that preferentially carry other divalent cations — such as magnesium and calcium — in fungi and humans. Inside cells, nickel is inserted into the active site of many enzymes such as hydrogenase, nickel superoxide dismutase, carbon monoxide dehydrogenase, cis-trans isomerase and urease. Toxic excess intracellular free nickel is neutralized by binding to negatively charged molecules such as polyphosphate and sequestration of nickel-containing complexes into vacuoles.

The nickel-containing protein urease is important in the pathophysiology of liver cirrhosis, peptic ulcers and urinary stones. Urease is produced by bacteria that infect the gastrointestinal and urinary tracts, including Helicobacter pylori and Proteus mirabilis. It breaks down urea and produces ammonia, which increases the pH of the surrounding environment from neutral to basic and becomes toxic in the liver, the stomach lining, the kidneys and the blood stream.

Cells transport, use and sequester zinc much as they do other divalent metals. Photosynthetic bacteria of the genus Acidiphilium contain a purple chlorophyll pigment that uses zinc as cofactor instead of the more common magnesium. Zinc-dependent phospholipases C in Clostridia, Bacillus or Listeria species may contribute to toxicity by breaking down host cell membranes. The coordination of one or more zinc ions by particular amino acids forms a zinc-finger motif that stabilizes the 3D structure of many proteins that bind DNA, such as nucleases and transcription factors.

Quira Zeidan

Quira Zeidan is the ASBMB’s education and public outreach coordinator.

Join the ASBMB Today mailing list

Sign up to get updates on articles, interviews and events.

Latest in Science

Science highlights or most popular articles

Early immune response may improve cancer immunotherapies
Journal News

Early immune response may improve cancer immunotherapies

January 23, 2020

University of Illinois at Chicago researchers and colleagues report a new mechanism for detecting foreign material during early immune responses.

Do sperm offer the uterus a secret handshake?
Journal News

Do sperm offer the uterus
a secret handshake?

January 22, 2020

Why does it take 200 million sperm to fertilize a single egg? A female immune response is one reason. A molecular handshake may help sperm survive the bombardment.

A new hotspot for cyclooxygenase inhibition
Lipid News

A new hotspot
for cyclooxygenase inhibition

January 21, 2020

Drugs like aspirin dampen inflammation by inhibiting certain enzymes but can have nasty gastrointestinal side effects, so enzymologists are investigating the structure of the enzymes’ active sites in hopes of designing more selective inhibitors.

Your blood type may influence your vulnerability to the winter vomiting virus
News

Your blood type may influence
your vulnerability to the winter
vomiting virus

January 19, 2020

Norovirus is very infectious, but not everyone is equally vulnerable. Whether you get sick or not may depend on your blood type.

The proteome of the cave bear
Journal News

The proteome of the cave bear

January 18, 2020

If a peptide mass spectrum is like a jigsaw puzzle, then a genome is the picture that researchers use to piece things together. But what do you do when there’s no picture to use as a guide?

Pulse points: 2020
Wellness

Pulse points: 2020

January 16, 2020

Research can spark change. Here are examples of how scientific inquiry exposes health risks and leads to new treatments for disease.