Given a passage and a query based on the passage, generate an unambiguous, concise and simple answer to the query from information in the passage. Note that the answer may not be present in exact form.

[EX Q]: summary: O2 could form a linear complex with the Fe atom, but then it would start to look more like a mineral Fe=O...O bond - a linear bond would be like a transition state to an iron oxide (rust). An Fe-O-O bent bond preserves more of the electronic character of the O2 molecule and promotes strong but reversible binding to Hemoglobin. The oxygen molecule forms a partial covalent bond with the iron in the heme (the ringlike molecule in the picture below ). The lone pair of electrons of the oxygen atom which forms the bond to the iron has a 120 degree angle with respect to the oxygen molecule itself. In chemistry we say it is sp2 hybridized. The heme iron serves as a source or sink of electrons during electron transfer or redox chemistry. In peroxidase reactions, the porphyrin molecule also serves as an electron source. In the transportation or detection of diatomic gases, the gas binds to the heme iron. During the detection of diatomic gases, the binding of the gas ligand to the heme iron induces conformational changes in the surrounding protein. Heme or haem is a coordination complex consisting of an iron ion coordinated to a porphyrin acting as a tetradentate ligand, and to one or two axial ligands. The definition is loose, and many depictions omit the axial ligands. The iron atom of heme is directly bonded to one of the histidines called the proximal histidine of the globin protein at the fifth coordination position. The oxygen binding site is present on the other side of the heme plane, at the sixth coordination position. Assuming that the deprotonated forms of HA and HZ bind selectively to the heme iron, the pH dependence of K D,app can be expressed by the following equation : K D, app =K D (1+[H +]/K a), where K D is a pH-independent dissociation constant and K a is the acid dissociation constant. Your question says "how is the heme molecule attached to globin protein". Let's first get the idea of what heme is. Heme is a non-protein group, which is the active site for haemoglobin, as well as myoglobin. Heme is held to the peptide portion (globin) of the protein by a combination of forces: 1 The coordination of iron by histidine nitrogen of the protein, 2 Hydrogen bonding, and. 3 Van der Waals forces between hydrophobic parts of the two molecules. Heme - Function. 1 Hemoproteins have diverse biological functions including the transportation of diatomic gases, chemical catalysis, diatomic gas detection, and electron transfer. The following genes are part of the chemical pathway for making heme: 1 ALAD: aminolevulinic acid, -, dehydratase (deficiency causes ala-dehydratase deficiency porphyria) 2 ALAS1: aminolevulinate, -, synthase 1. 3 ALAS2: aminolevulinate, -, synthase 2 (deficiency causes sideroblastic/hypochromic anemia) A2A: Quickly speaking, the heme group contains the famous iron ion that is in hemoglobin, that binds to and carries oxygen. The iron atom has a very strong covalent bond with the globular protein on the proximal histidine of the protein (the F8 histidine residue), on histidine's imidazole ring. Even with this strong covalent bond, the iron still has the ability to bind with oxygen via a dipolar or coordinate covalent bond. That is the electrostatic bond that hemoglobin is involved in, not the one that binds heme to the globin proteins in the first place. So the iron atom is not only involved in keeping the heme group attached to the globin proteins, but it is the functional oxygen-carrying component of the hemoglobin molecule. Query: how does iron bind to heme
[EX A]: The iron atom has a very strong covalent bond with the globular protein on the proximal histidine of the protein, on histidine's imidazole ring. Even with this strong covalent bond, the iron still has the ability to bind with oxygen via a dipolar or coordinate covalent bond. That is the electrostatic bond that hemoglobin is involved in, not the one that binds heme to the globin proteins in the first place. So the iron atom is not only involved in keeping the heme group attached to the globin proteins, but it is the functional oxygen-carrying component of the hemoglobin molecule.

[EX Q]: Lou Anna Simon will stay as president of Michigan State University despite increasing pressure for her to be fired. The school's board of trustees made the decision following a four-hour closed door meeting Friday. MSU board: Lou Anna Simon to stay as president, is 'right leader' for MSU There has been a tidal wave of calls for Simon to be fired for handling of the Larry Nassar matter. Post to Facebook 2005. Lou Anna Simon has a long history at Michigan State University, spanning over three decades. She started at MSU in 1970 as a graduate student, earning her doctorate in 1974. She then became a member of the MSU faculty and assistant director of the Office of Institutional Research. Simon has served as the provost and vice president for academic affairs since 1993. MSU board: Lou Anna Simon to stay as president, is 'right leader' for MSU. There has been a tidal wave of calls for Simon to be fired for handling of the Larry Nassar matter. Michigan State University President Lou Anna Simon will step down as leader of MSU, the school announced late Wednesday. As tragedies are politicized, blame is inevitable, she said in statement. As president, it is only natural that I am the focus of this anger. MSU's Lou Anna Simon arrives to court a day late and empathy short The board statement came as victims were standing in a front of a judge telling their stories. Simon said Friday she's going to continue to serve. President Simon has served with distinction as MSU's President for 13 years and has been a constant presence at the university for more than 40 years. She literally has devoted her entire professional life to this institution, and more than anyone else has helped make MSU a national and international leader in higher education. Lou Anna Simon has a long history at Michigan State University, spanning over three decades. She started at MSU in 1970 as a graduate student, earning her doctorate in 1974. She then became a member of the MSU faculty and assistant director of the Office of Institutional Research. Simon has served as the provost and vice president for academic affairs since 1993. Lou Anna K. Simon (b. 1947) President Michigan State University 2005 Lou Anna Simon has a long history at Michigan State University, spanning over three decades. She started at MSU in 1970 as a graduate student, earning her doctorate in 1974. She then became a member of the MSU faculty and assistant director of the Office of Institutional Research. MSU President Lou Anna Simon speaks to members of the press, victims, and their families Wednesday afternoon, Jan. 17, 2018, in Circuit Judge Rosemarie Aquilina's courtroom in Eaton County, Mich. (Photo: Matthew Dae Smith/Lansing State) Query: how long has lou anna simon been president of msu
[EX A]: President Simon has served with distinction as MSU's President for 13 years.

[EX Q]: There are a few good ways to get your PayPal funds released, but the most effective ways of doing so are: 1 Print your labels directly from eBay. By doing this, you (and your customer) will receive the tracking information ASAP. Because PayPal won't release the payment hold until the buyer rates and reviews you, this may be the best way to ensure you get your money in a timely manner. If, however, the package is lost in the mail (or the buyer is unresponsive) PayPal will automatically release your payment hold after 21 days. Unless, of course, the buyer is disputing your store and claiming you sold them junk. This will result in a loss of money, as well as endless amounts of stress. I sold several items with a new ebay and paypal account, all for less than $5. each, and paypal put the 21 day hold on me. I stopped using ebay about 5 years ago after my divorce, and i needed a new account and a new payupal account to sell on ebay. The Keys to Surviving the PayPal 21-Day Hold Policy. The "21 Day Hold Paypal Policy" has created a great deal of frustration for many eBay sellers. Below I have some recommendations for eBay sellers who are looking to ease the pain of this new policy: While everyone is at risk of a PayPal payment hold, there are ways to ensure that it doesn't happen to you. Or, if it does, it won't be often enough to bother you (or your business). Let's talk about some of the ways you can avoid payment holds in the future. eBay sellers who are relatively new (less than 100 feedback or member less than 6 months) or who have had little activity in the last year (fewer than 20 DSRs in the last 12 months) are, therefore, automatically subjected to the PayPal 21-Day hold even if their buyer satisfaction rating is greater than 95%. Keep in mind these few tips to ensure you'll be free of payment holds after a while: 1 Stay consistent with your customers. 2 Keep your DSRs around 4-5. 3 Don't change up your store too fast. 4 Print your labels directly from eBay (if you're selling there) and always enter your tracking number. Still not sure why PayPal has placed your payment on hold? Here are a few reasons to be on the lookout for: You're new to eBay. If you're not a valid seller and haven't sold more than a few items, PayPal will put your payment on hold to make sure you're delivering the item(s) in a timely manner. Whether you're new to eBay or not, PayPal holds will affect you all the same. While this may send you into a pit of despair at first, these holds won't last longer than 21 days. In fact, your payment may not even be on hold for that long! Payment holds can be lifted as the status of the shipped item is updated. Meaning: when your package is marked "shipped" and a tracking number is provided, the hold will be taken away. (If anything, the payment hold will be lifted when the buyer leaves feedback for you). Being a top-rated seller on eBay will come in handy in more ways than one. 1 A few ways to get to the top of eBay's seller list include: 2 Being an eBay seller for more than 6-12 months. 3 Above 95% feedback score. 4 Less than 20 DSRs (Detailed seller ratings) within 12 months. Query: how long does paypal hold payment for
[EX A]:
PayPal holds payment for 21 days.