Restriction enzyme or restriction endonuclease is a protein found in various strains of bacteria that recognize specific sequences in DNA and cut them into fragments. The restriction enzyme acts as a defense mechanism as it destroys the bacteriophages or phage.
Phage is a bacterial virus that infects bacteria by injecting its DNA into the bacteria. The restriction enzymes restrict the replication of this viral DNA by splitting it into useless fragments. It can also be separated from bacteria and used as a tool in the recombinant DNA technology.
Types of Restriction Enzymes
The restriction enzymes are recognized by the molecular biologists Werner Arber, Hamilton O Smith, and Daniel Nathans. They classified restriction enzymes into four types and designated as type I, II, III, and IV. This classification is mainly based on their subunit composition, recognition site and cofactor requirements.
Type I: Type I restriction enzymes or REases are large and complex proteins with three subunits: HsdR, HsdM, and HsdS). HsdR is essential for restriction, HsdM for methyltransferase activity and HsdS is necessary for DNA sequence recognition. The type I REases are multifunctional and capable of both cleavage and modification activity. But the cofactors- Hydrolyzed Adenosine Triphosphate, Magnesium, and S-Adenosyl Methionine- are required for the functional activity of this restriction enzymes.
Type II: Type II restriction enzymes cleave DNA at specific sequences and they can produce discrete restriction fragments. They use only Magnesium as a cofactor for recognizing and cleaving DNA. They can use in the laboratory for cloning and DNA analysis. In the late 1990s, the subcategories of Type II restriction enzymes were discovered based on the variation from main characteristics of Type II REases. The subcategories include Type IIB, Type IIE, Type IIF, Type IIG, Type IIM, Type IIS and Type IIT.
Type III: Type III restriction enzymes are also the restriction and modification enzymes. They also require cofactors- Hydrolyzed Adenosine Triphosphate and S-Adenosyl Methionine- to perform restriction and methylation activities. These enzymes composed of two subunits and they are also multifunctional.
Type IV: Type IV restriction enzymes perform their restriction and modification activities with the cofactor S-Adenosyl Methionine. Type IV restriction enzymes are capable of identifying irregular DNA sequences and restrict the replication of them.
Uses of Restriction Enzymes in Biotechnology
Restriction enzymes are able to cleave double-stranded DNA into fragments at specific sequences to prevent the replication of viral DNA. This functional activity of restriction enzymes led to the extensive use of these enzymes in the Genetic Engineering. Restriction enzymes use as an important tool in the recombinant DNA technology to generate recombinant DNA molecules, which are molecules that consist of genes from two different organisms. Typically, the DNA obtained from the bacteria called plasmid join to the DNA from another gene of interest for cloning. Restriction enzymes have been widely used for identifying humans and other species. It also has applications in modern genetics. They can also be used to map the entire genome and to confirm the identity of a particular DNA fragment.
Chipmakers in drought-hit Taiwan order water trucks to prepare for ‘the worst’
TAIPEI (Reuters) – Taiwan chipmakers are buying water by the truckload for some of their foundries as the island widens restrictions on water supply amid a drought that could exacerbate a chip supply crunch for the global auto industry.
Some auto makers have already been forced to trim production, and Taiwan had received requests for help to bridge the shortage of auto chips from countries including the United States and Germany.
Taiwan, a key hub in the global technology supply chain for giants such as Apple Inc, will begin on Thursday to further reduce water supply for factories in central and southern cities where major science parks are located.
Water levels in several reservoirs in the island’s central and southern region stand at below 20%, following months of scant rainfall and a rare typhoon-free summer.
“We have planned for the worst,” Taiwan Economy Minister Wang Mei-hua told reporters on Tuesday. “We hope companies can reduce water usage by 7% to 11%.”
With limited rainfall forecast for the months ahead, Taiwan Water Corporation this week said the island has entered the “toughest moment”.
Taiwan Semiconductor Manufacturing Co Ltd (TSMC), the world’s largest contract chipmaker, this week started ordering small amounts of water by the truckload to supply some of its facilities across the island.
“We are making preparations for our future water demand,” TSMC told Reuters, describing the move as a “pressure test”. The chip giant said it has seen no impact on production. Both Vanguard International Semiconductor Corporation and United Microelectronics Corp signed contracts with water trucks and said there was no impact on production.
Vanguard said it has started a drill to truck water to its facilities in the northern city of Hsinchu.
Taiwanese technology companies have long complained about a chronic water shortage, which became more acute after factories expanded production following a Sino-U.S. trade war.
(Reporting By Yimou Lee; additional reporting by Jeanny Kao; Editing by Simon Cameron-Moore)
Oil slips after U.S. crude stocks rise amid deep freeze hit to refiners
By Sonali Paul
MELBOURNE (Reuters) – Oil prices fell in early trade on Wednesday after industry data showed U.S. crude inventories unexpectedly rose last week as a deep freeze in the southern states curbed demand from refineries that were forced to shut.
Crude stockpiles rose by 1 million barrels in the week to Feb. 19, the American Petroleum Institute (API) reported on Tuesday, against estimates for a draw of 5.2 million barrels in a Reuters poll.
API data showed refinery crude runs fell by 2.2 million bpd.
U.S. West Texas Intermediate (WTI) crude futures were down 55 cents or 0.9% at $61.12 a barrel at 0136 GMT, after slipping 3 cents on Tuesday.
Brent crude futures fell 38 cents, or 0.6%, to $64.99 a barrel, erasing Tuesday’s 13 cents gain.
Investors will be awaiting confirmation from the U.S. Energy Information Administration later on Wednesday that crude inventories rose last week, despite the hit to shale oil production amid the unprecedented icy spell in the U.S. south.
“The key question is how quickly does U.S. oil supply recover. It looks like supply will recover faster than refineries, and supply is going to outpace demand in the next few weeks. That will give negative weight to the market,” Commonwealth Bank analyst Vivek Dhar said.
The price retreat is being seen as a pause following a rally of more than 26% to 13-month highs in both Brent and WTI since the start of the year.
Prices have jumped due to the U.S. supply disruption and supply discipline by the Organization of the Petroleum Exporting Countries and allies, together called OPEC+, led by an extra 1 million bpd cut by Saudi Arabia.
At the same time stimulus spending to boost growth, investors rotating into commodities, and hopes that the rollout of vaccinations could lead to an easing of pandemic restrictions are all buoying oil prices.
(Reporting by Sonali Paul; Editing by Edwina Gibbs)
Oil settles mixed amid post-storm uncertainty
By Laura Sanicola
NEW YORK (Reuters) – Oil prices settled near year-long highs on Tuesday on signs that global coronavirus restrictions were being eased, although concerns about the pace of a U.S. economic recovery and the return of Texas oil production kept gains in check.
U.S. crude settled down 3 cents to $61.67 a barrel, still close to its highest levels since January 2020. Brent crude <LCOc1> settled up 13 cents, or 0.2%, to $65.37 a barrel.
Both contracts rose more than $1 earlier before retreating.
Shale oil producers and refiners in the southern United States are slowly resuming production after 2 million barrels per day (bpd) of crude output and nearly 20% of U.S. refining capacity shut down because of last week’s winter storm.
Traffic at the Houston ship channel was slowly returning to normal. Production, however, was not expected to fully restart soon and some shale producers forecast lower oil output in the first quarter.
Some oil production may never come back, commodities merchant Trafigura said on Tuesday.
After the cold snap, U.S. crude oil stockpiles were also seen falling for a fifth straight week, while the inventories of refined products also declined last week, an extended Reuters poll showed.
“It appears that last week’s severe cold spell and related Texas power outage could be affecting the weekly EIA data into the middle of next month,” said Jim Ritterbusch, president of Ritterbusch and Associates in Galena, Illinois.
There were also concerns over the U.S. economic recovery, which the chair of the Federal Reserve, Jerome Powell, said remained “uneven and far from complete.”
He said it would be “some time” before the central bank considered changing policies it had adopted to help the country back to full employment.
Commerzbank analyst Eugen Weinberg said the recent oil price rise was buoyed by upbeat price forecasts from U.S. brokers.
Goldman Sachs expects Brent prices to reach $70 per barrel in the second quarter from the $60 it predicted previously, and $75 in the third quarter from $65 forecast earlier.
Morgan Stanley, which expects Brent to reach $70 in the third quarter, said new COVID-19 cases were falling while “mobility statistics are bottoming out and are starting to improve”.
Bank of America said Brent prices could temporarily spike to $70 in the second quarter.
(Reporting by Laura Sanicola in New York; Additional reporting by Bozorgmehr Sharafedin in London and Jessica Jaganathan in Singapore; Editing by Matthew Lewis and Mark Heinrich)
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